build(deps): bump opencv-contrib-python in /benchmark

Bumps [opencv-contrib-python](https://github.com/opencv/opencv-python) from 4.2.0.32 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-contrib-python
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

benchmark/requirements.txt

@@ -1,3 +1,3 @@
 numpy
 matplotlib
-opencv-contrib-python==4.2.0.32
+opencv-contrib-python==4.8.1.78