JP-3857 Saturation code style changes

[jemorrison]

Partially resolves JP-3857

This PR updates the saturation step to conform to code style rules.

Tasks

• If you have a specific reviewer in mind, tag them.
• add a build milestone, i.e. Build 12.0 (use the latest build if not sure)
• Does this PR change user-facing code / API? (if not, label with no-changelog-entry-needed)
  • write news fragment(s) in changes/: echo "changed something" > changes/<PR#>.<changetype>.rst (see changelog readme for instructions)
  • update or add relevant tests
  • update relevant docstrings and / or docs/ page
  • start a regression test and include a link to the running job ([click here for instructions]
    Regression test passed: https://github.com/spacetelescope/RegressionTests/actions/runs/14601643348
    (https://github.com/spacetelescope/RegressionTests/blob/main/docs/running_regression_tests.md))
    • Do truth files need to be updated ("okified")?
      • after the reviewer has approved these changes, run okify_regtests to update the truth files
• if a JIRA ticket exists, make sure it is resolved properly

[jemorrison]

running regression tests

[emolter]

Thanks Jane, this looks great, I've added some additional suggestions

[codecov]

Codecov Report

Attention: Patch coverage is 72.54902% with 14 lines in your changes missing coverage. Please review.

Project coverage is 75.62%. Comparing base (670170d) to head (71b11d3).
Report is 733 commits behind head on main.

Files with missing lines	Patch %	Lines
jwst/saturation/x_irs2.py	16.66%	10 Missing ⚠️
jwst/saturation/saturation_step.py	75.00%	3 Missing ⚠️
jwst/saturation/saturation.py	96.15%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #9405      +/-   ##
==========================================
+ Coverage   75.60%   75.62%   +0.01%     
==========================================
  Files         368      368              
  Lines       36916    36908       -8     
==========================================
+ Hits        27911    27912       +1     
+ Misses       9005     8996       -9     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[jemorrison]

@emolter When I look at the files changed - I see all the modifications you suggested.

[jemorrison]

@emolter Hopefully you will see all the changes now.
I am not sure why you did not before

[emolter]

All my comments have been addressed, thanks Jane!

I added one additional small note about the input model parameter we were having a back-and-forth about, but it's up to you whether to incorporate it, it's not a big deal either way

[melanieclarke]

Looks good! One small typo in your last change + one rephrasing suggestion.

[melanieclarke]

Looks good, thanks!