mirrorshades v0.2.0

[pbrkr]

Development release of mirrorshades.

• Move project to GitHub, the new project URL is https://github.com/unnecessary-abstraction/mirrorshades.

• Add GitHub mirroring support.

• Prune deleted branches when updating a mirrored git repository.

• Support multiple attempts when running custom commands.

• Add config validation using desert and marshmallow.

• Update and expand README file.

• Improve developer & contributor workflows with the addition of automatic linting & formatting. These checks are ran in GitHub Actions
  when contributing to the project via a pull request. They can also be ran locally using pre-commit.

• Satisfy the REUSE Specification to ensure licensing is clear.

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This discussion was created from the release mirrorshades v0.2.0.