Run GitHub Actions locally #79

New features

• Locally run the project's GitHub actions using act

Improvements

• Add brew to a new, custom dev container (required by act)

Notes

Command to run the test workflow locally with act:

act -j test

GitHub documentation on custom dev containers:
https://docs.github.com/en/codespaces/setting-up-your-project-for-codespaces/introduction-to-dev-containers