Update macOS version in CI workflow

Author: amontoison

.github/workflows/CI.yml

@@ -30,7 +30,7 @@ jobs:
         os:
           - ubuntu-latest
           - windows-latest
-          - macos-13
+          - macos-15-intel
         arch:
           - x64
         include:
@@ -47,7 +47,7 @@ jobs:
         with:
           compiler: 'gcc'
           version: '14'
-        if: matrix.os == 'macos-latest' || matrix.os == 'macos-13'
+        if: matrix.os == 'macos-latest' || matrix.os == 'macos-15-intel'
       - uses: julia-actions/setup-julia@v2
         with:
           version: ${{ matrix.version }}