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

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

Author: pre-commit-ci[bot]

strings/join.py

@@ -45,6 +45,7 @@ def join(separator: str, separated: list[str]) -> str:
 
     return joined
 
+
 if __name__ == "__main__":
     from doctest import testmod