fix(github-actions): pin versions to sha

[billhimmelsbach]

Due to some recent supply chain attacks, Lamin would prefer if we locked the github actions to SHAs instead of just the version number. I used the same script that cf.gov used over here, thanks @chosak!

Changes

• Instead of using a version number, locks github actions to SHAs

Testing

1. Do the github actions still work? Yes!
2. Do the tests still pass? Yes!

[PatrickGoRaft]

LGTM.