MassInstallAction: Install the CI workflow on this repository

[timholy]

This pull request sets up the CI workflow on this repository.

[codecov[bot]]

Codecov Report

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[oscardssmith]

@timholy we should probably update and merge this, right?

[fingolfin]

This definitely should be updated and merged. Also the badge in README.md should be updated.

Let me know if I can help.