Fix flake8 style reports

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>

tests/test_patch.py

@@ -40,6 +40,7 @@ def test_patch(tmpdir):
     kas.kas(['shell', 'test.yml', '-c', 'true'])
     os.chdir(prev_dir)
 
+
 def test_patch_update(tmpdir):
     """
         Test that patches are applied correctly after switching refspec from

tests/test_refspec.py

@@ -22,7 +22,6 @@
 
 import os
 import shutil
-import subprocess
 from kas import kas
 from kas.libkas import run_cmd