[cleanup] Consistent style for file heads

test/test_postprocessors.py

@@ -1,4 +1,5 @@
 #!/usr/bin/env python3
+
 # Allow direct execution
 import os
 import sys
@@ -6,6 +7,7 @@ import unittest
 
 sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
 
+
 from yt_dlp import YoutubeDL
 from yt_dlp.compat import compat_shlex_quote
 from yt_dlp.postprocessor import (