remove python-dateutil dependency in favor of QDateTime

gotify_tray/gui/MainApplication.py

@@ -1,5 +1,4 @@
 import getpass
-import locale
 import logging
 import os
 import platform
@@ -407,8 +406,6 @@ def start_gui():
 
     init_logger(logger)
 
-    locale.setlocale(locale.LC_TIME, "")
-
     # prevent multiple instances
     if (app.acquire_lock() or "--no-lock" in sys.argv) and verify_server():
         app.init_ui()