Restore macOS CMake configuration.

PiperOrigin-RevId: 684435872

Author: protobuf-github-bot

.github/workflows/test_cpp.yml

@@ -346,11 +346,11 @@ jobs:
       fail-fast: false   # Don't cancel all jobs if one fails.
       matrix:
         include:
-          # TODO: investigate and fix
-          # - name: MacOS CMake
-          #   os: macos-12
-          #   flags: -DCMAKE_CXX_STANDARD=14
-          #   cache-prefix: macos-cmake
+          - name: MacOS CMake
+            os: macos-13
+            flags: -DCMAKE_CXX_STANDARD=14
+            cache-prefix: macos-cmake
+            continuous-only: true
           - name: Windows CMake
             os: windows-2022
             flags: >-