Housekeeping: Add linter, CI

[pygeek]

What was done

• Update this library to follow PEP8.
• Update this library to use a linter (black).
• Update this library to use Continuous Integration (GitHub Actions).
• Add pre-commit for local development.

What was NOT done

Breaking changes. Changes that affect library behavior.

Rationale

• Following PEP8, and more generally, Python idiosyncrasies increases readability and maintainability.
• Adding a linter, specifically black, identifies PEP8 violations and automatically formats (locally) code to conform with PEP8.
• Adding Continuous Integration (via Github Actions) ensures that violations are presented during a Pull Request and can be made to be a prerequisite to merging into develop / main (must be done by repository's maintainer)).
• Adding pre-commit allows developers to ensure that linters are run automatically. By running pre-commit install it installs .git/hooks (by default, on commit).

[gerrrg]

I may revisit this. Will likely pull in the linter/GH action in one PR and then update the source files in another.