build(deps): bump opencv-python-headless in /backend

Bumps [opencv-python-headless](https://github.com/opencv/opencv-python) from 4.10.0.84 to 4.11.0.86.
- [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
  update-type: version-update:semver-minor
...

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

backend/requirements.txt

@@ -73,7 +73,7 @@ psutil
 sentencepiece
 soundfile==0.12.1
 
-opencv-python-headless==4.10.0.84
+opencv-python-headless==4.11.0.86
 rapidocr-onnxruntime==1.3.24
 rank-bm25==0.2.2