fixup! Format Python code with psf/black push

Author: github-actions

graphs/karger.py

@@ -60,7 +60,9 @@ def partition_graph(graph: Dict[str, List[str]]) -> Set[Tuple[str, str]]:
         for neighbor in uv_neighbors:
             graph_copy[neighbor].append(uv)
 
-        contracted_nodes[uv] = {node for node in contracted_nodes[u].union(contracted_nodes[v])}
+        contracted_nodes[uv] = {
+            node for node in contracted_nodes[u].union(contracted_nodes[v])
+        }
 
         # Remove nodes u and v.
         del graph_copy[u]