amc: build a bottle for macOS 12 Monterey (x86_64 only)

Author: maelvls

.github/workflows/tests.yml

@@ -18,8 +18,9 @@ jobs:
           # Remember to re-enable it one day.
           #
           # - ubuntu-latest
-          
+
           # https://github.com/actions/virtual-environments/#available-environments
+          - macos-12
           - macos-11
           - macos-10.15
     runs-on: ${{ matrix.os }}