Disable upgrade tests unless
$RUN_UPGRADE_TESTS is set. Add MacOS test jobs that run either in the asdf/asdf repo or if explicitly requested with
$RUN_MACOS_JOBS. Requires that the MacOS runner be tagged with
macos and has all the Lisps already installed.
Leaving as a WIP until asdf/asdf is configured with a MacOS runner.
Tests for ECL on MacOS modified until https://gitlab.com/embeddable-common-lisp/ecl/-/issues/600 is dealt with.