ci: Update macos runner version

macos-13 image will be retired shortly.

Author: ales-erjavec

.github/workflows/run-tests-workflow.yml

@@ -55,7 +55,7 @@ jobs:
             test-env: "PyQt6~=6.9.0 PyQt6-Qt6~=6.9.0"
 
           # macOS
-          - os: macos-13
+          - os: macos-14
             python-version: "3.10"
             test-env: "PyQt5~=5.15.0"