Feature/remove opencv python

[lorenzomammana]

Summary

This PR aims to remove the "opencv-python" dependency in favor of the headless version. This is done as installing both is

1. Not correct
2. Problematic on Windows as the two packages might conflict

Type of Change

Please select the one relevant option below:

• Refactor

Checklist

Please confirm that the following tasks have been completed:

• I have tested my changes locally and they work as expected. (Please describe the tests you performed.)
• I have added unit tests for my changes, or updated existing tests if necessary.
• I have updated the documentation, if applicable.
• I have installed pre-commit and run locally for my code changes.