Fix Qt QAction import

In PySide2 QAction is available under `PySide2.QtWidgets`[1] whereas in
PySide6 it resides under `PySide6.QtGui`[2].

Closes #788

[1]: https://doc.qt.io/qtforpython-5/PySide2/QtWidgets/QAction.html#PySide2.QtWidgets.PySide2.QtWidgets.QAction
[2]: https://doc.qt.io/qtforpython-6/PySide6/QtGui/QAction.html

CHANGELOG.md

@@ -10,6 +10,7 @@ since 0.4.1, and this project adheres to [Semantic Versioning](https://semver.or
 ### Fixed
 
 - Fix a deprecation warning in PySide6, thanks to [@naglis](https://github.com/naglis) ([issue #595](https://github.com/freedomofpress/dangerzone/issues/595))
+- Make update notifications work in systems with PySide2, thanks to [@naglis](https://github.com/naglis) ([issue #788](https://github.com/freedomofpress/dangerzone/issues/788))
 
 ## Dangerzone 0.6.1
 

dangerzone/gui/main_window.py

@@ -14,11 +14,14 @@
 # FIXME: See https://github.com/freedomofpress/dangerzone/issues/320 for more details.
 if typing.TYPE_CHECKING:
     from PySide2 import QtCore, QtGui, QtSvg, QtWidgets
+    from PySide2.QtWidgets import QAction
 else:
     try:
         from PySide6 import QtCore, QtGui, QtSvg, QtWidgets
+        from PySide6.QtGui import QAction
     except ImportError:
         from PySide2 import QtCore, QtGui, QtSvg, QtWidgets
+        from PySide2.QtWidgets import QAction
 
 from .. import errors
 from ..document import SAFE_EXTENSION, Document
@@ -267,7 +270,7 @@ def handle_updates(self, report: UpdateReport) -> None:
             )
             sep = hamburger_menu.insertSeparator(hamburger_menu.actions()[0])
             # FIXME: Add red bubble next to the text.
-            error_action = QtGui.QAction("Update error", hamburger_menu)  # type: ignore [attr-defined]
+            error_action = QAction("Update error", hamburger_menu)
             error_action.setIcon(
                 QtGui.QIcon(self.load_svg_image("hamburger_menu_update_dot_error.svg"))
             )
@@ -288,7 +291,7 @@ def handle_updates(self, report: UpdateReport) -> None:
             )
 
             sep = hamburger_menu.insertSeparator(hamburger_menu.actions()[0])
-            success_action = QtGui.QAction("New version available", hamburger_menu)  # type: ignore [attr-defined]
+            success_action = QAction("New version available", hamburger_menu)
             success_action.setIcon(
                 QtGui.QIcon(
                     self.load_svg_image("hamburger_menu_update_dot_available.svg")