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

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

tests/module/mobject/test_graph.py

@@ -1,8 +1,10 @@
 from __future__ import annotations
+
 import pytest
 
 from manim import DiGraph, Graph, Scene, Text, tempconfig
 
+
 def test_graph_creation():
     vertices = [1, 2, 3, 4]
     edges = [(1, 2), (2, 3), (3, 4), (4, 1)]
@@ -101,11 +103,13 @@ def test_custom_animation_mobject_list():
         assert str(G) == "Undirected graph on 3 vertices and 0 edges"
         assert scene.mobjects == [G]
 
+
 def test_tree_layout_no_root_error():
     with pytest.raises(ValueError) as excinfo:
         G = Graph([1, 2, 3], [(1, 2), (2, 3)], layout="tree")
     assert str(excinfo.value) == "The tree layout requires the root_vertex parameter"
 
+
 def test_tree_layout_not_tree_error():
     with pytest.raises(ValueError) as excinfo:
         G = Graph([1, 2, 3], [(1, 2), (2, 3), (3, 1)], layout="tree", root_vertex=1)