update type hinting

gotify_tray/gui/widgets/ImagePopup.py

@@ -8,7 +8,7 @@ settings = Settings("gotify-tray")
 
 
 class ImagePopup(QtWidgets.QLabel):
-    def __init__(self, filename: str, pos: QtCore.QPoint, link: str = None):
+    def __init__(self, filename: str, pos: QtCore.QPoint, link: str | None = None):
         """Create and show a pop-up image under the cursor
 
         Args:

gotify_tray/gui/widgets/MessageWidget.py

@@ -23,7 +23,7 @@ class MessageWidget(QtWidgets.QWidget, Ui_Form):
         app: QtWidgets.QApplication,
         parent: QtWidgets.QWidget,
         message_item: MessagesModelItem,
-        icon: QtGui.QIcon = None,
+        icon: QtGui.QIcon | None = None,
     ):
         super(MessageWidget, self).__init__(parent)
         self.app = app