Bump XCode versions

Author: sjrdc

.github/workflows/ci-macos.yml

@@ -10,13 +10,13 @@ jobs:
         include:
           - CMAKE_OPTIONS: '-DWITH_WERROR=OFF -DSKIP_PORTABILITY_TEST=ON -DSKIP_PERFORMANCE_COMPARISON=ON'
             COMPILER: 'clang++'
-            XCODE_VERSION: 11
-            NAME: macos-latest-clang-xcode11
+            XCODE_VERSION: 15
+            NAME: macos-latest-clang-xcode15
 
           - CMAKE_OPTIONS: '-DWITH_WERROR=OFF -DSKIP_PORTABILITY_TEST=ON -DSKIP_PERFORMANCE_COMPARISON=ON'
             COMPILER: 'clang++'
-            XCODE_VERSION: 12
-            NAME: macos-latest-clang-xcode12
+            XCODE_VERSION: 16
+            NAME: macos-latest-clang-xcode16
     name: ${{ matrix.name }}
 
     steps: