Bump opencv-python-headless in /3.test_cases/9.nemo-multimodal (#414)

Bumps [opencv-python-headless](https://github.com/opencv/opencv-python) from 4.8.0.74 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]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

3.test_cases/9.nemo-multimodal/requirements.txt

@@ -7,4 +7,4 @@ pynvml==11.4.1
 requests==2.32.0
 tqdm==4.66.3
 zstandard==0.15.2
-opencv-python-headless==4.8.0.74
+opencv-python-headless==4.8.1.78