JP-3423: fixed array shape mismatch in pixel_replace mingrad algorithm

[emolter]

Resolves JP-3423

Closes #7960

This PR addresses a bug that would cause crashes when the mingrad algorithm for pixel replacement was applied to NIRSpec data. The error was due to an inappropriate assumption about the input array shape, which was fixed in a single line.

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

Attention: Patch coverage is 0% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 75.21%. Comparing base (4cc0ac1) to head (96d47d4).
Report is 7 commits behind head on master.

Files	Patch %	Lines
jwst/pixel_replace/pixel_replace.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #8312      +/-   ##
==========================================
+ Coverage   75.15%   75.21%   +0.05%     
==========================================
  Files         470      474       +4     
  Lines       38604    38810     +206     
==========================================
+ Hits        29014    29192     +178     
- Misses       9590     9618      +28     

Flag	Coverage Δ		*Carryforward flag
nightly	77.37% <ø> (-0.03%)	⬇️	Carriedforward from 75645eb

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[hbushouse]

@emolter Looks like this needs a regression test run.

[emolter]

Just started this one, sorry about that:

regtest run

edit: all tests passed

[hbushouse]

Code change is fine and regtest run is clean.