Add github actions workflow

[caleb-sitton-inl]

This adds a github actions workflow that is triggered by pushes and PRs onto main. The workflow serves as a wrapper around the already-configured pre-commit workflow, which runs the test suite using pytest as well as linting and formatting with ruff, a copyright header check, and some basic built-in helper checks. Two modifications have also been made to the pre-commit config:

• mypy is now run as part of the precommit hook to catch any typing errors
• the --check arg has been removed from the ruff format call because it resulted in needing an extra, manual ruff format call before allowing a commit, which was deemed unnecessarily complex

Closes #2.

[j-bryan]

Looks good. It'll be nice to finally have automated CI on the project!