CI: Update macOS Runner (Latest)

The old `macos-11` image is now removed. Update to
running release `macos-latest`.

.github/workflows/macos.yml

@@ -11,13 +11,14 @@ jobs:
   # Build PICSAR tests, PICSAR python bindings, and Kokkos examples
   tutorials-macos:
     name: QED with tests, python bindings, Kokkos examples
-    runs-on: macos-11
+    runs-on: macos-latest
     steps:
     - uses: actions/checkout@v2
     - name: Dependencies
       run: .github/workflows/dependencies/dependencies_mac.sh
     - name: Build & Test
       run: |
+        which clang++
         cmake -S multi_physics/QED                \
             -B build                              \
             -DCMAKE_VERBOSE_MAKEFILE=ON           \