Fully deprecate Python 2

[kiwiz]

• [x] Remove Python 2 references
• [x] Integrate ruff
• [x] Migrate to Github Actions
• [x] Fix errors with Sphinx docs
• [x] Review Sphinx docs
• [x] Testing

Backwards incompatible changes:

• Bump minimum Python version to 3.10
• Keep.login/Keep.resume/APIAuth.login no longer return a bool
• The device_id parameter previously defaulted to get_mac(), which returned an int. This has been updated to cast the int to a hexadecimal string

[kiwiz]

Let's just support Python 3.10+ for all the nice new type annotation features :firecracker:

[wizpig64]

There are some hacks to get the 3.10 syntax working as far back as 3.6, and 3.9 doesn't go EOL until 2025. But if you want to keep the version list short for simplicity, I'd support that decision. I try to keep my keep project running on python's latest.

[kiwiz]

That's a neat (ab?)use of codecs. I'll stick with 3.10 for now and see if anyone has issues.