Call App.initialize() in the setUp phase of GlobalConfiguration test

Otherwise it will crash that the cls._app is not created.

Author: jkonecny12

tests/units/main/global_configuration_test.py

@@ -28,6 +28,9 @@
 
 class GlobalConfiguration_TestCase(unittest.TestCase):
 
+    def setUp(self):
+        App.initialize()
+
     def tearDown(self):
         App.initialize()