Run with new macos-15-intel runner

Author: marcprux

.github/workflows/ci.yml

@@ -34,10 +34,10 @@ jobs:
           #- os: 'macos-26'
           #  swift: '6.2'
           #  arch: 'arm64-v8a'
-          - os: 'macos-13'
+          - os: 'macos-15-intel'
             swift: '6.1'
             arch: 'x86_64'
-          - os: 'macos-13'
+          - os: 'macos-15-intel'
             swift: '6.2'
             arch: 'x86_64'
     runs-on: ${{ matrix.os }}