fixup! Add skew heap data structure.

Author: Phil9l

Diff for: data_structures/heap/skew_heap.py

@@ -1,6 +1,7 @@
 #!/usr/bin/env python3
 
 from __future__ import annotations
+
 from typing import Generic, Iterable, List, Optional, TypeVar
 
 __all__ = ["SkewHeap"]