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

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

Author: pre-commit-ci[bot]

Diff for: data_structures/disjoint_set/union_find.py

@@ -68,6 +68,7 @@ def union(self, a: int, b: int) -> bool:
 
 if __name__ == "__main__":
     import doctest
+
     doctest.testmod()
 
     uf = UnionFind(10)