TypeError: startswith first arg must be str or a tuple of str, not bytes

```
  File "/usr/local/lib/python3.9/dist-packages/patch_ng.py", line 454, in parse
    while not fe.is_empty and not fe.line.startswith(b"--- "):
TypeError: startswith first arg must be str or a tuple of str, not bytes
```

Probably the best solution is to just drop python 2.