Create python template

[clbarrell]

Needs checking and editing.

Anyone is free to take this over and complete it.

Resolves #18

This PR adds a Python pipeline that:

• installs dependencies using pip
• runs tests using pytest
• runs linting with Ruff, which seems to be the more popular linter.
• annotates the build based on junit output

[dannymidnight]

Righto, this one is now ready for review.