Bump opencv-python from 3.4.4.19 to 4.2.0.32

Bumps [opencv-python](https://github.com/skvark/opencv-python) from 3.4.4.19 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
...

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Author: dependabot[bot]

requirements.txt

@@ -1,6 +1,6 @@
 openslide-python==1.1.1
 Pillow==6.2.0
-opencv-python==3.4.4.19
+opencv-python==4.2.0.32
 shapely==1.6.4
 pydaily==0.4.0
 pycontour==1.4.0