DEV/MNT: migrate to GitHub Actions and pyproject.toml [LCLSPC-603]

[klauer]

Description

• Upgrading by way of https://github.com/pcdshub/pcds-python-migration-tools
• pytmc has been migrated to use setuptools-scm, replacing versioneer, as its version-string management tool of choice.
• pytmc has been migrated to use the modern pyproject.toml, replacing setup.py and related files.
• Older language features and syntax found in the repository have been updated to Python 3.9+ standards by way of pyupgrade.
• Sphinx 6.0 is now supported for documentation building.
• docs-versions-menu is now used for documentation deployment on GitHub Actions.
• Removed the no-longer-required doctr documentation deployment key.
• pyupgrade was used to update annotations, though there might not have been many here
• pycln was used to clean up imports
• Using the same Jira ticket number so we can pretend it was done as part of the same effort, when in fact we forgot about poor old pytmc
• Moved lcls-twincat-motion in test suite to latest master
• Reformatted codebase with black

Motivation and Context

• Migrating because we want to migrate our projects from Travis CI.

How Has This Been Tested?

• GitHub Actions

Where Has This Been Documented?

This PR and Jira LCLSPC-603