Fix Windows CI: use os._exit() to bypass Qt cleanup crash

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: Axel Hörteborn

.github/workflows/python-app.yml

@@ -89,4 +89,4 @@ jobs:
         set PATH=C:\OSGeo4W\apps\qgis\bin;%PATH%
         set QT_QPA_PLATFORM=offscreen
         set QT_OPENGL=software
-        python3 -m pytest tests -s || if %ERRORLEVEL% equ -1073740791 exit /b 0
+        python3 -c "import sys, os; import pytest; code = pytest.main(['tests', '-s']); os._exit(code)"