build(deps): Bump opencv-python from 4.5.1.48 to 4.8.1.78

Bumps [opencv-python](https://github.com/opencv/opencv-python) from 4.5.1.48 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
...

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

requirements.txt

@@ -16,5 +16,5 @@ Sphinx==4.2.0
 six
 xmltodict==0.10.2
 wheel
-opencv-python==4.5.1.48 ; sys_platform == "win32"
+opencv-python==4.8.1.78 ; sys_platform == "win32"
 opencv-python ; sys_platform == "linux"