HTTPS-proxy [Errno 111] Connection refused

<!-- Summary. -->
While all other protocols are working, I can't access an URL using an HTTPS-proxy ([StackOverflow](https://stackoverflow.com/questions/71150284/python-request-https-proxy-errno-111-connection-refused))

## Expected Result
Open an HTTPS-URL using HTTPS-proxy.
<!-- What you expected. -->

## Actual Result
[Errno 111] Connection refused

```
---------------------------------------------------------------------------
ConnectionRefusedError                    Traceback (most recent call last)
[/usr/local/lib/python3.7/dist-packages/urllib3/connection.py](https://localhost:8080/#) in _new_conn(self)
    158             conn = connection.create_connection(
--> 159                 (self._dns_host, self.port), self.timeout, **extra_kw)
    160 

14 frames
[/usr/local/lib/python3.7/dist-packages/urllib3/util/connection.py](https://localhost:8080/#) in create_connection(address, timeout, source_address, socket_options)
     79     if err is not None:
---> 80         raise err
     81 

[/usr/local/lib/python3.7/dist-packages/urllib3/util/connection.py](https://localhost:8080/#) in create_connection(address, timeout, source_address, socket_options)
     69                 sock.bind(source_address)
---> 70             sock.connect(sa)
     71             return sock

ConnectionRefusedError: [Errno 111] Connection refused

During handling of the above exception, another exception occurred:

NewConnectionError                        Traceback (most recent call last)
[/usr/local/lib/python3.7/dist-packages/urllib3/connectionpool.py](https://localhost:8080/#) in urlopen(self, method, url, body, headers, retries, redirect, assert_same_host, timeout, pool_timeout, release_conn, chunked, body_pos, **response_kw)
    593             if is_new_proxy_conn:
--> 594                 self._prepare_proxy(conn)
    595 

[/usr/local/lib/python3.7/dist-packages/urllib3/connectionpool.py](https://localhost:8080/#) in _prepare_proxy(self, conn)
    804         conn.set_tunnel(self._proxy_host, self.port, self.proxy_headers)
--> 805         conn.connect()
    806 

[/usr/local/lib/python3.7/dist-packages/urllib3/connection.py](https://localhost:8080/#) in connect(self)
    300         # Add certificate verification
--> 301         conn = self._new_conn()
    302         hostname = self.host

[/usr/local/lib/python3.7/dist-packages/urllib3/connection.py](https://localhost:8080/#) in _new_conn(self)
    167             raise NewConnectionError(
--> 168                 self, "Failed to establish a new connection: %s" % e)
    169 

NewConnectionError: <urllib3.connection.VerifiedHTTPSConnection object at 0x7fc4f55256d0>: Failed to establish a new connection: [Errno 111] Connection refused

During handling of the above exception, another exception occurred:

MaxRetryError                             Traceback (most recent call last)
[/usr/local/lib/python3.7/dist-packages/requests/adapters.py](https://localhost:8080/#) in send(self, request, stream, timeout, verify, cert, proxies)
    449                     retries=self.max_retries,
--> 450                     timeout=timeout
    451                 )

[/usr/local/lib/python3.7/dist-packages/urllib3/connectionpool.py](https://localhost:8080/#) in urlopen(self, method, url, body, headers, retries, redirect, assert_same_host, timeout, pool_timeout, release_conn, chunked, body_pos, **response_kw)
    637             retries = retries.increment(method, url, error=e, _pool=self,
--> 638                                         _stacktrace=sys.exc_info()[2])
    639             retries.sleep()

[/usr/local/lib/python3.7/dist-packages/urllib3/util/retry.py](https://localhost:8080/#) in increment(self, method, url, response, error, _pool, _stacktrace)
    398         if new_retry.is_exhausted():
--> 399             raise MaxRetryError(_pool, url, error or ResponseError(cause))
    400 

MaxRetryError: HTTPSConnectionPool(host='google.com', port=443): Max retries exceeded with url: / (Caused by ProxyError('Cannot connect to proxy.', NewConnectionError('<urllib3.connection.VerifiedHTTPSConnection object at 0x7fc4f55256d0>: Failed to establish a new connection: [Errno 111] Connection refused')))

During handling of the above exception, another exception occurred:

ProxyError                                Traceback (most recent call last)
[<ipython-input-5-0042a445fda6>](https://localhost:8080/#) in <module>()
      5 print(proxy_url)
      6 
----> 7 r = requests.get('https://google.com/', proxies = {protocol: proxy_url})
      8 r.status_code

[/usr/local/lib/python3.7/dist-packages/requests/api.py](https://localhost:8080/#) in get(url, params, **kwargs)
     73     """
     74 
---> 75     return request('get', url, params=params, **kwargs)
     76 
     77 

[/usr/local/lib/python3.7/dist-packages/requests/api.py](https://localhost:8080/#) in request(method, url, **kwargs)
     59     # cases, and look like a memory leak in others.
     60     with sessions.Session() as session:
---> 61         return session.request(method=method, url=url, **kwargs)
     62 
     63 

[/usr/local/lib/python3.7/dist-packages/requests/sessions.py](https://localhost:8080/#) in request(self, method, url, params, data, headers, cookies, files, auth, timeout, allow_redirects, proxies, hooks, stream, verify, cert, json)
    527         }
    528         send_kwargs.update(settings)
--> 529         resp = self.send(prep, **send_kwargs)
    530 
    531         return resp

[/usr/local/lib/python3.7/dist-packages/requests/sessions.py](https://localhost:8080/#) in send(self, request, **kwargs)
    643 
    644         # Send the request
--> 645         r = adapter.send(request, **kwargs)
    646 
    647         # Total elapsed time of the request (approximately)

[/usr/local/lib/python3.7/dist-packages/requests/adapters.py](https://localhost:8080/#) in send(self, request, stream, timeout, verify, cert, proxies)
    511 
    512             if isinstance(e.reason, _ProxyError):
--> 513                 raise ProxyError(e, request=request)
    514 
    515             if isinstance(e.reason, _SSLError):

ProxyError: HTTPSConnectionPool(host='google.com', port=443): Max retries exceeded with url: / (Caused by ProxyError('Cannot connect to proxy.', NewConnectionError('<urllib3.connection.VerifiedHTTPSConnection object at 0x7fc4f55256d0>: Failed to establish a new connection: [Errno 111] Connection refused')))
```
<!-- What happened instead. -->

## Reproduction Steps

Here is also a google [colab](https://colab.research.google.com/drive/1mlRyfHna4jH1R27SYJoRO9udoQYu5UsB?usp=sharing) that reproduces this issue.

```python
import requests
import random

PROXY_LIST_URL = 'https://proxylist.geonode.com/api/proxy-list?limit=50&page=1&sort_by=lastChecked&sort_type=desc&protocols=https'

proxies = requests.get(PROXY_LIST_URL).json()['data']

proxy = random.choice(proxies)

protocol = proxy['protocols'][0]
proxy_url = f"{protocol}://{proxy['ip']}:{proxy['port']}"
print(proxy_url)

r = requests.get('https://google.com', proxies = {protocol: proxy_url})
print(r.status_code)
```

## System Information

    $ python -m requests.help

```json
{
  "chardet": {
    "version": "3.0.4"
  },
  "charset_normalizer": {
    "version": "2.0.12"
  },
  "cryptography": {
    "version": ""
  },
  "idna": {
    "version": "2.10"
  },
  "implementation": {
    "name": "CPython",
    "version": "3.7.12"
  },
  "platform": {
    "release": "5.4.144+",
    "system": "Linux"
  },
  "pyOpenSSL": {
    "openssl_version": "",
    "version": null
  },
  "requests": {
    "version": "2.27.1"
  },
  "system_ssl": {
    "version": "1010100f"
  },
  "urllib3": {
    "version": "1.24.3"
  },
  "using_charset_normalizer": false,
  "using_pyopenssl": false
}
```

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please provide some basic information about your system (Python version,
operating system, &c). -->


Hi there! Thanks for opening this issue. Unfortunately, it seems this is a request for help instead of a report of a defect in the project. Please use [StackOverflow](https://stackoverflow.com) for general usage questions instead and only report defects here.

Additionally, in the future, please search **closed and** open issues before creating new ones that are duplicates.