Fix OpenCV compatibility problems

[AdeelH]

Overview

This PR fixes the below error

  File "/opt/conda/lib/python3.7/site-packages/cv2/__init__.py", line 9, in <module>
    from .cv2 import _registerMatType
ImportError: cannot import name '_registerMatType' from 'cv2.cv2' (/opt/conda/lib/python3.7/site-packages/cv2/cv2.cpython-37m-x86_64-linux-gnu.so)

that started cropping up in recent builds during unit testing, even though no OpenCV-related changes have been made recently.

See other discussions of this error below:

• ImportError: cannot import name '_registerMatType' from 'cv2.cv2' opencv/opencv-python#591
• https://stackoverflow.com/questions/70537488/cannot-import-name-registermattype-from-cv2-cv2

Checklist

• Added needs-backport label if PR is bug fix that applies to previous minor release
• Ran scripts/format_code and committed any changes
• Documentation updated if needed
• PR has a name that won't get you publicly shamed for vagueness

Testing Instructions

• build Docker image
• Run unit tests
• If unit tests succeed, the issue has been resolved.

[codecov]

Codecov Report

Merging #1323 (e3c45ec) into master (fc181a6) will not change coverage.
The diff coverage is n/a.

❗ Current head e3c45ec differs from pull request most recent head b03fc51. Consider uploading reports for the commit b03fc51 to get more accurate results

@@           Coverage Diff           @@
##           master    #1323   +/-   ##
=======================================
  Coverage   59.20%   59.20%           
=======================================
  Files         171      171           
  Lines        7935     7935           
=======================================
  Hits         4698     4698           
  Misses       3237     3237           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update fc181a6...b03fc51. Read the comment docs.

[AdeelH]

(Fixed a typo in one of the commit messages)