Implement support GitHub actions.

[euronion]

Implement GitHub actions for the repository.

Describe the feature you'd like to see

Wishlist and ideas:

• black or PEP 8 automatic code formatting (git functionality to have continued support for blame/diff)
• jupyter notebooks without output files.
• REUSE compliance check

[euronion]

Potentially also of interest:

• Automatically publish on conda-forge: https://github.com/fcakyon/conda-publish-action
• Automatically publish on pypi: https://github.com/pypa/gh-action-pypi-publish

[FabianHofmann]

covered by #416