[pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

Author: pre-commit-ci[bot]

docs/source/html_builder.py

@@ -16,6 +16,7 @@
 
 class MypyHTMLBuilder(StandaloneHTMLBuilder):
     strict_file: Path
+
     def __init__(self, app: Sphinx, env: BuildEnvironment) -> None:
         super().__init__(app, env)
         self._ref_to_doc = {}