Update macosx.yml

Author: jwillemsen

.github/workflows/macosx.yml

@@ -19,7 +19,7 @@ jobs:
     strategy:
       matrix:
         cxxstd: ["17"]
-        os: [macos-12, macos-13]
+        os: [macos-13, macos-14]
         include:
           - platform_file: include $(ACE_ROOT)/include/makeinclude/platform_macosx.GNU
     runs-on: ${{ matrix.os }}