Update GitHub Actions for macOS

Author: zuckschwerdt

.github/workflows/ci.yml

@@ -145,11 +145,6 @@ jobs:
                       os: macos-14
                       python3_ver: '3.9'
 
-                    - cc: clang
-                      cxx: clang++
-                      os: macos-13
-                      python3_ver: '3.9'
-
                     - cc: clang
                       cxx: clang++
                       os: macos-15