fix linter

fix linter
7 jobs for 1218-smartplaylist_backend in 2 minutes and 32 seconds (queued for 8 seconds)
Name Stage Failure
failed
flake8 Lint
api/funkwhale_api/playlists/utils.py:76:1: W293 blank line contains whitespace
api/funkwhale_api/playlists/utils.py:83:9: F841 local variable 'e' is assigned to but never used
api/funkwhale_api/playlists/utils.py:94:13: F841 local variable 'e' is assigned to but never used
api/funkwhale_api/playlists/utils.py:105:13: F841 local variable 'e' is assigned to but never used
api/funkwhale_api/playlists/serializers.py:129:5: E301 expected 1 blank line, found 0
api/funkwhale_api/playlists/serializers.py:142:47: F821 undefined name 'playlist_id'
api/funkwhale_api/playlists/serializers.py:153:1: W391 blank line at end of file
Cleaning up file based variables
ERROR: Job failed: exit code 1
failed
black Lint
         if track_id:
track_list.append(track_id.id)
added_track_count = added_track_count + 1

would reformat api/funkwhale_api/playlists/utils.py
Oh no! 💥 💔 💥
2 files would be reformatted, 433 files would be left unchanged.
Cleaning up file based variables
ERROR: Job failed: exit code 1