python: Whitespace fixes from autopep8.

Generated by autopep8, with the setup.cfg configuration from #14532.
I’m not sure why pycodestyle didn’t already flag these.

Signed-off-by: Anders Kaseorg <anders@zulipchat.com>

zerver/lib/bugdown/include.py

@@ -26,6 +26,7 @@ class IncludeCustomPreprocessor(IncludePreprocessor):
     JsonableError exception. The rest of the functionality is identical
     to the original markdown_include extension.
     """
+
     def run(self, lines: List[str]) -> List[str]:
         done = False
         while not done: