Motivation:
Swift 6.1 has been released, we should add it to our CI coverage.
Modifications:
Add additional Swift 6.1 jobs where appropriate in main.yml,
pull_request.yml
Result:
Improved test coverage.
Motivation:
* Improve test coverage
Modifications:
Enable macOS CI to be run on pull request commits and make the use of
the nightly runner pool for main.yml jobs explicit.
Result:
Improved test coverage.