Bump opencv-python from 3.4.2.16 to 4.2.0.32 in /trackers/PoseFlow

Bumps [opencv-python](https://github.com/skvark/opencv-python) from 3.4.2.16 to 4.2.0.32.
- [Release notes](https://github.com/skvark/opencv-python/releases)
- [Commits](https://github.com/skvark/opencv-python/commits)

---
updated-dependencies:
- dependency-name: opencv-python
  dependency-type: direct:production
...

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

trackers/PoseFlow/requirements.txt

@@ -1,6 +1,6 @@
 numpy==1.14.5
 scipy==1.1.0
-opencv_python==3.4.2.16
+opencv_python==4.2.0.32
 opencv_contrib_python==3.4.2.16
 matplotlib==2.2.2
 tqdm==4.23.4