Remove Swift 3.1.1 action runtime and associated tests and
documentation. This runtime version has long since been replaced by
Swift 4.x and no longer appears to even build (unavailable
dependencies cause Docker build to hang).
Also add CHANGELOG for Swift 4.2 and 5.1 and update NOTICE date.
Remove Swift 3.1.1 action runtime and associated tests and documentation. This runtime version has long since been replaced by Swift 4.x and no longer appears to even build (unavailable dependencies cause Docker build to hang).
Also add CHANGELOG for Swift 4.2 and 5.1 and update NOTICE date.