qml: fix flake errors

electrum/gui/qml/plugins.py

@@ -12,7 +12,7 @@ class PluginQObject(QObject):
 
     _busy = False
 
-    def __init__(self, plugin, parent: 'ElectrumGuiApplication'):
+    def __init__(self, plugin, parent):
         super().__init__(parent)
         self.plugin = plugin
         self.app = parent

electrum/plugins/labels/qml.py

@@ -117,7 +117,7 @@ class Plugin(LabelsPlugin):
             _wallet.labelsUpdated.emit()
 
     @hook
-    def init_qml(self, gui: 'ElectrumGui'):
+    def init_qml(self, gui):
         self.logger.debug(f'init_qml hook called, gui={str(type(gui))}')
         self._app = gui.app
         # important: QSignalObject needs to be parented, as keeping a ref