GitHub Actions changed their latest images for MacOS to use the aarch64
instead of the x86_64 architecture. The SWT tests are currently failing
because they still assume macos-latest to be an x86_64 architecture and
therefore use the according SWT binaries.

With this change, the used GitHub actions runner is changed from
macos-latest to macos-latest-large to ensure that still the x86_64 build
is used. This is supposed to restore the existing purpose of the
configuration. Changing to or adding an aarch64 runner for MacOS can be
done subsequently.