test: Cleanup tests and use relative imports

tests/mainloop/__init__.py

@@ -0,0 +1,5 @@
+# -*- coding: utf-8 -*-
+"""Init file for test group."""
+__author__ = "Sven Sager"
+__copyright__ = "Copyright (C) 2024 Sven Sager"
+__license__ = "GPLv2"

tests/mainloop/test_mainloop.py

@@ -8,8 +8,8 @@ from os.path import dirname
 from time import sleep
 
 import revpimodio2
-from tests import TestRevPiModIO
-from tests.helper import ExitThread, ChangeThread
+from .. import TestRevPiModIO
+from ..helper import ExitThread, ChangeThread
 
 event_data = (None, None)