Consider replacing our requests-unixsocket fork with requests-unixsocket2

Consider switching to https://gitlab.com/thelabnyc/requests-unixsocket2 rather than using my fork that I set up to fix some integration issues. Here is the project announcement:

Since this project seems to be abandoned, but its longevity is important to my team, we've forked the project as requests-unixsocket2. It should be a drop in replacement for this package.

PyPI: https://pypi.org/project/requests-unixsocket2/0.4.0/
Repository: https://gitlab.com/thelabnyc/requests-unixsocket2
Clone of this PR: https://gitlab.com/thelabnyc/requests-unixsocket2/-/merge_requests/1

We've migrated this PR there, merged it, and released to PyPI as part of v0.4.0.

We're using it production on several actively developed projects, so I anticipate keeping it compatible with up-to-date requests/urllib3. But we're not at the moment looking to add a ton of new features/refactoring/etc, if that's what you mean. PRs are of course welcome if you have something in mind.