type hint application wrapper monkeypatch

ignore method assignment. Currently mypy cannot check this.
Related upstream issues:
  - python/mypy#2427
  - python/mypy#708

dangerzone/gui/__init__.py

@@ -7,7 +7,7 @@
 
 import click
 import colorama
-from PySide2 import QtCore, QtWidgets
+from PySide2 import QtCore, QtGui, QtWidgets
 
 from ..global_common import GlobalCommon
 from .common import GuiCommon
@@ -29,9 +29,10 @@ def __init__(self) -> None:
 
         self.original_event = self.app.event
 
-        def monkeypatch_event(event: QtCore.QEvent) -> bool:
+        def monkeypatch_event(arg__1: QtCore.QEvent) -> bool:
+            event = arg__1  # oddly Qt calls internally event by "arg__1"
             # In macOS, handle the file open event
-            if event.type() == QtCore.QEvent.FileOpen:
+            if isinstance(event, QtGui.QFileOpenEvent):
                 # Skip file open events in dev mode
                 if not hasattr(sys, "dangerzone_dev"):
                     self.document_selected.emit(event.file())
@@ -42,7 +43,7 @@ def monkeypatch_event(event: QtCore.QEvent) -> bool:
 
             return self.original_event(event)
 
-        self.app.event = monkeypatch_event
+        self.app.event = monkeypatch_event  # type: ignore [assignment]
 
 
 @click.command()