fix: Fix lint.

Author: RoyYang0714

.gitmodules

@@ -1,4 +1,4 @@
 [submodule "vis4d-test-data"]
-	path = tests/vis4d-test-data
-	url = git@github.com:SysCV/vis4d-test-data.git
+    path = tests/vis4d-test-data
+    url = git@github.com:SysCV/vis4d-test-data.git
     branch = main

tests/data/transforms/mosaic_test.py

@@ -4,7 +4,6 @@
 import unittest
 
 import numpy as np
-import torch
 from PIL import Image
 
 from tests.util import get_test_file