Merge pull request #2511 from WenmuZhou/update_requirements

Update requirements

requirements.txt

@@ -3,9 +3,8 @@ scikit-image==0.17.2
 imgaug==0.4.0
 pyclipper
 lmdb
-opencv-python==4.2.0.32
 tqdm
 numpy
 visualdl
 python-Levenshtein
-opencv-contrib-python
\ No newline at end of file
+opencv-contrib-python==4.2.0.32
\ No newline at end of file