Bump opencv-python-headless from 4.7.0.72 to 4.8.0.74 (#1300)

Bumps [opencv-python-headless](https://github.com/opencv/opencv-python) from 4.7.0.72 to 4.8.0.74.
- [Release notes](https://github.com/opencv/opencv-python/releases)
- [Commits](https://github.com/opencv/opencv-python/commits)

---
updated-dependencies:
- dependency-name: opencv-python-headless
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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