return opencv-python to a hard dependency

[zacharyburnett]

Closes #7409

This PR adds opencv-python to the hard dependencies in setup.cfg. This will fix installation issues for CRDS context >= jwst_1068.pmap (which enables snowball detection), but prevent installation on platforms that do not have a compiled binary for opencv-python, such as MacOS Mojave + Python 3.10.

If / when an alternative to opencv-python is implemented (JP-3120), this dependency can be removed.

Checklist for maintainers

• added entry in CHANGES.rst within the relevant release section
• updated or added relevant tests
• updated relevant documentation
• added relevant milestone
• added relevant label(s)
• ran regression tests, post a link to the Jenkins job below.
  How to run regression tests on a PR
• Make sure the JIRA ticket is resolved properly

[codecov]

Codecov Report

Patch coverage has no change and project coverage change: -0.01 ⚠️

Comparison is base (08b318e) 77.60% compared to head (ec77e21) 77.59%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #7499      +/-   ##
==========================================
- Coverage   77.60%   77.59%   -0.01%     
==========================================
  Files         452      452              
  Lines       36095    36095              
==========================================
- Hits        28010    28009       -1     
- Misses       8085     8086       +1     

Flag	Coverage Δ
nightly	77.60% <ø> (-0.01%)	⬇️
unit	49.56% <ø> (-0.01%)	⬇️

see 1 file with indirect coverage changes

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[hbushouse]

Looks OK, but let's be sure to get a regtest run against this branch before we approve and merge.

[zacharyburnett]

regtest run is at https://plwishmaster.stsci.edu:8081/blue/organizations/jenkins/RT%2FJWST-Developers-Pull-Requests/detail/JWST-Developers-Pull-Requests/603/pipeline

[hbushouse]

All of the failures from the regtest are expected differences due to more pixels being flagged by the snowball/shower correction in the jump step (which then propagates all the way downstream). So it looks good. I'm merging!