Fix test workflow to use docker compose v2, as v1 now retired

Apparently "docker-compose" was deprecated over 6 months ago and is
starting to be phased out in favor of "docker compose".  Without this,
test runners are getting:

  home/runner/work/_temp/0af6641a-337b-4651-8ca4-fef3529091af.sh: line 1:
  docker-compose: command not found

See https://github.com/orgs/community/discussions/116610 for details

.github/workflows/tests.yaml

@@ -66,9 +66,9 @@ jobs:
           GITHUB_USER: ${{ github.actor }}
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           CONTAINER: ${{ matrix.container }}
-        run: if [[ !( "${CONTAINER}" =~ osx-* ) ]] ; then docker-compose build "test-${CONTAINER}" ; fi
+        run: if [[ !( "${CONTAINER}" =~ osx-* ) ]] ; then docker compose build "test-${CONTAINER}" ; fi
       - name: Test ${{ matrix.name }}
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           CONTAINER: ${{ matrix.container }}
-        run: if [[ !( "${CONTAINER}" =~ osx-* ) ]]; then docker-compose run "test-${CONTAINER}" ; else bash test/scripts/test_osx.sh ; fi
+        run: if [[ !( "${CONTAINER}" =~ osx-* ) ]]; then docker compose run "test-${CONTAINER}" ; else bash test/scripts/test_osx.sh ; fi