2.28.0: sphinx warnings `reference target not found`

On building my packages I'm using `sphinx-build` command with `-n` switch which shows warmings about missing references. These are not critical issues.
Here is the output with warnings:

<details>

```console
+ /usr/bin/sphinx-build -n -T -b man docs build/sphinx/man
Running Sphinx v5.0.1
WARNING: Invalid configuration value found: 'language = None'. Update your configuration to a valid langauge code. Falling back to 'en' (English).
making output directory... done
loading intersphinx inventory from https://docs.python.org/3/objects.inv...
loading intersphinx inventory from https://urllib3.readthedocs.io/en/latest/objects.inv...
building [mo]: targets for 0 po files that are out of date
building [man]: all manpages
updating environment: [new config] 15 added, 0 changed, 0 removed
reading sources... [100%] user/quickstart
looking for now-outdated files... none found
pickling environment... done
checking consistency... done
writing... python-requests.3 { user/install user/quickstart user/advanced user/authentication community/recommended community/faq community/out-there community/support community/vulnerabilities community/release-process community/updates api dev/contributing dev/authors } /home/tkloczko/rpmbuild/BUILD/requests-2.28.0/requests/models.py:docstring of requests.models.Response.json:: WARNING: py:exc reference target not found: requests.exceptions.JSONDecodeError
/home/tkloczko/rpmbuild/BUILD/requests-2.28.0/requests/adapters.py:docstring of requests.adapters.BaseAdapter.send:3: WARNING: py:class reference target not found: PreparedRequest
/home/tkloczko/rpmbuild/BUILD/requests-2.28.0/requests/adapters.py:docstring of requests.adapters.HTTPAdapter:3: WARNING: py:class reference target not found: Session
/home/tkloczko/rpmbuild/BUILD/requests-2.28.0/requests/adapters.py:docstring of requests.adapters.HTTPAdapter.add_headers:9: WARNING: py:class reference target not found: PreparedRequest
/home/tkloczko/rpmbuild/BUILD/requests-2.28.0/requests/adapters.py:docstring of requests.adapters.HTTPAdapter.build_response:6: WARNING: py:class reference target not found: PreparedRequest
/home/tkloczko/rpmbuild/BUILD/requests-2.28.0/requests/adapters.py:docstring of requests.adapters.HTTPAdapter.get_connection:: WARNING: py:class reference target not found: urllib3.ConnectionPool
/home/tkloczko/rpmbuild/BUILD/requests-2.28.0/requests/adapters.py:docstring of requests.adapters.HTTPAdapter.request_url:10: WARNING: py:class reference target not found: PreparedRequest
/home/tkloczko/rpmbuild/BUILD/requests-2.28.0/requests/adapters.py:docstring of requests.adapters.HTTPAdapter.send:3: WARNING: py:class reference target not found: PreparedRequest
/home/tkloczko/rpmbuild/BUILD/requests-2.28.0/requests/adapters.py:docstring of requests.adapters.HTTPAdapter.send:: WARNING: py:class reference target not found: urllib3 Timeout object
/home/tkloczko/rpmbuild/BUILD/requests-2.28.0/requests/utils.py:docstring of requests.utils.add_dict_to_cookiejar:: WARNING: py:class reference target not found: CookieJar
/home/tkloczko/rpmbuild/BUILD/requests-2.28.0/requests/cookies.py:docstring of requests.cookies.cookiejar_from_dict:: WARNING: py:class reference target not found: CookieJar
/home/tkloczko/rpmbuild/BUILD/requests-2.28.0/requests/cookies.py:docstring of collections.abc.MutableMapping.pop:: WARNING: py:class reference target not found: v, remove specified key and return the corresponding value.
/home/tkloczko/rpmbuild/BUILD/requests-2.28.0/requests/cookies.py:docstring of collections.abc.MutableMapping.popitem:: WARNING: py:class reference target not found: (k, v), remove and return some (key, value) pair
/home/tkloczko/rpmbuild/BUILD/requests-2.28.0/requests/cookies.py:docstring of collections.abc.MutableMapping.setdefault:: WARNING: py:class reference target not found: D.get(k,d), also set D[k]=d if k not in D
done
build succeeded, 15 warnings.
```
</details>

You can peak on fixes that kind of issues in other projects
https://github.com/latchset/jwcrypto/pull/289
https://github.com/click-contrib/sphinx-click/commit/abc31069
https://github.com/latchset/jwcrypto/pull/289
https://github.com/RDFLib/rdflib-sqlalchemy/issues/95
https://github.com/sissaschool/elementpath/commit/bf869d9e
https://github.com/jaraco/cssutils/issues/21


Thanks @kloczek, we'll take a look.