Merge pull request matplotlib#22479 from MAKOMO/main

FIX: adds _enum qualifier for QColorDialog.ShowAlphaChannel. Closes matplotlib#22471.

Author: tacaswell

lib/matplotlib/backends/qt_editor/_formlayout.py

@@ -71,7 +71,7 @@ def __init__(self, parent=None):
     def choose_color(self):
         color = QtWidgets.QColorDialog.getColor(
             self._color, self.parentWidget(), "",
-            QtWidgets.QColorDialog.ShowAlphaChannel)
+            _enum("QtWidgets.QColorDialog.ColorDialogOption").ShowAlphaChannel)
         if color.isValid():
             self.set_color(color)