move to macos-15

Author: flagarde

.github/workflows/macOS.yml

@@ -126,8 +126,8 @@ jobs:
         run: cmake --install ${{ env.CMAKE_BINARY_PREFIX }} --prefix ${{ env.CMAKE_INSTALL_PREFIX }} --config ${{ env.CMAKE_BUILD_TYPE }}
 
   gcc:
-    runs-on: macos-14
-    name: macos-14 gcc-${{ matrix.version }} (c++${{ matrix.standard }})
+    runs-on: macos-15
+    name: macos-15 gcc-${{ matrix.version }} (c++${{ matrix.standard }})
     strategy:
       fail-fast: false
       matrix: