refactor: track background tasks in application lifecycle and clean up codebase

tests/test_ytdl_source.py

@@ -2,7 +2,6 @@ from __future__ import annotations
 
 import struct
 import unittest
-from unittest.mock import MagicMock
 
 import discord
 
@@ -62,6 +61,5 @@ class TestYTDLSource(unittest.TestCase):
         self.assertEqual(right, -32768)
 
 
-
 if __name__ == "__main__":
     unittest.main()