[requests] Allow "connect" timeout to be None in timeout configuration tuple

[filipsnastins]

Individual values of the timeout configuration tuple (connect timeout, read timeout) can be set to None, making the timeout indefinite.

Previously, only the read timeout could be set to None.

[github-actions]

Diff from mypy_primer, showing the effect of this PR on open source code:

discord.py (https://github.com/Rapptz/discord.py)
- discord/ext/commands/hybrid.py:508: error: Overlap between argument names and ** TypedDict items: "description", "name"  [misc]
+ discord/ext/commands/hybrid.py:508: error: Overlap between argument names and ** TypedDict items: "name", "description"  [misc]
- discord/ext/commands/hybrid.py:629: error: Overlap between argument names and ** TypedDict items: "name", "description"  [misc]
+ discord/ext/commands/hybrid.py:629: error: Overlap between argument names and ** TypedDict items: "description", "name"  [misc]

[brianschubert]

Following the calls, None does seem to be accepted in the first tuple entry:

• https://github.com/psf/requests/blob/v2.32.4/src/requests/adapters.py#L652-L664
• https://github.com/urllib3/urllib3/blob/4dad8713f127d0b9b63ecb30712de2847c39df42/src/urllib3/util/timeout.py#L66-L84

And it works at runtime:

uv run -w 'requests==2.32.4' python -c 'import requests; r = requests.get("https://example.com", timeout=(None, 1)); print(r.status_code)'
200

I don't see anything contrary in the docs or in the original PR discussion (#7696).

So, LGTM! Thanks!