ci: use macos-14 because macos-11 is not available anymore (#291)

Author: radoering

.github/workflows/main.yml

@@ -24,7 +24,7 @@ jobs:
           - os: Windows
             image: windows-2022
           - os: macOS
-            image: macos-11
+            image: macos-14
       fail-fast: false
     defaults:
       run: