Bump opencv-python-headless from 4.5.2.54 to 4.8.1.78

Bumps [opencv-python-headless](https://github.com/opencv/opencv-python) from 4.5.2.54 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-headless
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

requirements.txt

@@ -56,7 +56,7 @@ urllib3==1.26.19
 vine==5.1.0
 watchdog==0.10.3
 zipp==3.19.1
-opencv-python-headless==4.5.2.54
+opencv-python-headless==4.8.1.78
 zbar-py==1.0.4
 drf-spectacular==0.20.2
 beautifulsoup4==4.10.0