GitHub Actions only supports PyQt5 not PyQt6

Author: Dennis-van-Gils

.github/workflows/python-package.yml

@@ -17,7 +17,7 @@ jobs:
       fail-fast: false
       matrix:
         python-version: ["3.8", "3.9", "3.10"]
-        qt-lib: [pyqt5, pyqt6, pyside2, pyside6]
+        qt-lib: [pyqt5, pyside2]
     env:
       DISPLAY: ':99.0'