Once `setup-gap@v3`, `run-pkg-tests@v4`, etc., are out, update all `gap-actions` to use latest versions of our workflows

[fingolfin]

CC @stertooy @Joseph-Edwards

[stertooy]

I think it'd also be a good idea to test actions on windows-latest (combined with setup-cygwin@v2), since that should hopefully work now without the need for a different branch.

[fingolfin]

... and also on macOS...

[wilfwilson]

Yes, would be very nice.