Bump opencv-python from 4.4.0.42 to 4.8.1.78 in /examples/research_projects/visual_bert (#33251)

Bump opencv-python in /examples/research_projects/visual_bert

Bumps [opencv-python](https://github.com/opencv/opencv-python) from 4.4.0.42 to 4.8.1.78.
- [Release notes](https://github.com/opencv/opencv-python/releases)
- [Commits](https://github.com/opencv/opencv-python/commits)

---
updated-dependencies:
- dependency-name: opencv-python
  dependency-type: direct:production
...

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examples/research_projects/visual_bert/requirements.txt

@@ -48,7 +48,7 @@ nbformat==5.0.7
 nest-asyncio==1.4.0
 notebook==6.4.12
 numpy==1.22.0
-opencv-python==4.4.0.42
+opencv-python==4.8.1.78
 packaging==20.3
 pandas==1.1.2
 pandocfilters==1.4.2