Undefined name: Arrow() --> manim.Arrow() like line 62

% `flake8 . --count --select=E9,F63,F7,F82,Y --show-source --statistics`
```
./git_sim/git_sim_add.py:46:58: F821 undefined name 'Arrow'
                        secondColumnArrowMap[x.a_path] = Arrow(stroke_width=3, color=self.scene.fontColor)
                                                         ^
1     F821 undefined name 'Arrow'
1
```

Author: cclauss

git_sim/git_sim_add.py

@@ -43,7 +43,7 @@ def populate_zones(self, firstColumnFileNames, secondColumnFileNames, thirdColum
                 for name in self.scene.args.name:
                     if name == x.a_path:
                         thirdColumnFileNames.add(x.a_path)
-                        secondColumnArrowMap[x.a_path] = Arrow(stroke_width=3, color=self.scene.fontColor)
+                        secondColumnArrowMap[x.a_path] = m.Arrow(stroke_width=3, color=self.scene.fontColor)
         try:
             for y in self.repo.index.diff("HEAD"):
                 if "git-sim_media" not in y.a_path: