Bump opencv-python from 4.5.2.52 to 4.8.1.78

Bumps [opencv-python](https://github.com/opencv/opencv-python) from 4.5.2.52 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] <[email protected]>

requirements.txt

@@ -5,7 +5,7 @@ itsdangerous==2.0.1
 Jinja2==3.0.1
 Keras==2.4.3
 Keras-Preprocessing==1.1.2
-opencv-python==4.5.2.52
+opencv-python==4.8.1.78
 pandas==1.2.4
 Pillow==8.3.2
 protobuf==3.14.0