fix: blocked Exception_Window by setting modality

If some dialogs are open while an exception was raised the input of
Exception_Window is blocked and the user cannot click the button to
submit the issue report. Only if the other dialog is closed
Exception_Window starts responding. By setting the modality of
`Exception_Windows` to `ApplicationModal` the `Exception_Window` will
get the 'highest priority' and accepts input even if other dialogs are
open.

electrum/gui/qt/exception_window.py

@@ -99,6 +99,9 @@ class Exception_Window(BaseCrashReporter, QWidget, MessageBoxMixin, Logger):
 
         main_box.addLayout(buttons)
 
+        # prioritizes the window input over all other windows
+        self.setWindowModality(QtCore.Qt.WindowModality.ApplicationModal)
+
         self.setLayout(main_box)
         self.show()