Repository: urllib3/urllib3

Issue:
`python_requires` prevents install of recent urllib3 when using Poetry
### Subject

re: https://github.com/urllib3/urllib3/pull/1309#issuecomment-356650894

I no longer see the suggestion of including `<4` in the link referenced earlier in that PR (content relocated to https://packaging.python.org/en/latest/guides/distributing-packages-using-setuptools/#python-requires). Its inclusion is causing `1.22` to be installed.

I use `poetry` to manage dependencies for https://github.com/cj81499/advent-of-code, and today I got a dependabot alert for urllib3 (CVE-2018-20060).

I tried a `poetry update`, but poetry did not update urllib. `poetry add urllib3@latest` revealed the problem.

```command
> poetry add urllib3@latest
Using version ^1.26.12 for urllib3

Updating dependencies
Resolving dependencies... (0.0s)

The current project's Python requirement (>=3.9) is not compatible with some of the required packages Python requirement:
  - urllib3 requires Python >=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*, !=3.5.*, <4, so it will not be satisfied for Python >=4

Because urllib3 (1.26.12) requires Python >=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*, !=3.5.*, <4
 and no versions of urllib3 match >1.26.12,<2.0.0, urllib3 is forbidden.
So, because aoc-cj depends on urllib3 (^1.26.12), version solving failed.

  • Check your dependencies Python requirement: The Python requirement can be specified via the `python` or `markers` properties
    
    For urllib3, a possible solution would be to set the `python` property to ">=3.9,<4"

    https://python-poetry.org/docs/dependency-specification/#python-restricted-dependencies,
    https://python-poetry.org/docs/dependency-specification/#using-environment-markers
```

As a result of this change, I've been quietly stuck on `urllib3 v1.22` without even realizing it.

As suggested by poetry, I've changed _my_ python requirement from ">=3.9" to ">=3.9,<4" to be able to update, but I'm not sure there's a good reason to restrict the supported python versions to `<4`. Like I mentioned earlier, it seems this is no longer recommended by the Python docs.

In addition, since it didn't set a `python_requires`, a (future) Python 4 user might try to install urllib3 and get `v1.22`(!), which seems like pretty undesirable behavior to me.

_Originally posted by @cj81499 in https://github.com/urllib3/urllib3/issues/1309#issuecomment-1301625738_

### Environment

poetry 1.2.2

OS macOS-12.6-x86_64-i386-64bit
Python 3.9.15
urllib3 1.22

### Steps to Reproduce

- Install poetry
- Clone https://github.com/cj81499/advent-of-code
- Checkout commit `a8fecd3`
- run `poetry install`
- run `poetry show urllib3`
- Observe that version 1.22 is installed

### Expected Behavior

Latest urllib3 (`1.26.12` at time of writing) is installed

### Actual Behavior

urllib3 `1.22` is installed


Discussion:

Resolving patch:
diff --git a/setup.py b/setup.py
--- a/setup.py
+++ b/setup.py
@@ -82,7 +82,7 @@
     ],
     package_dir={"": "src"},
     requires=[],
-    python_requires=">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*, !=3.5.*, <4",
+    python_requires=">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*, !=3.5.*",
     extras_require={
         "brotli": [
             "brotli>=1.0.9; (os_name != 'nt' or python_version >= '3') and platform_python_implementation == 'CPython'",


Test patch: