Re-enable macOS CI (aarch64-darwin) with modern nixpkgs

Author: srid

.github/workflows/ci.yaml

@@ -9,7 +9,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-latest]
+        os: [ubuntu-latest, macos-14]
     env:
       MAINLINE: refs/heads/master
       DOCKERTAG: latest