TST: Add Sersic2D to NON_FINITE_LM_MODELS - #18381

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Alright then, let's roll with it. Thanks @WilliamJamieson

Owee, I'm MrMeeseeks, Look at me.

There seem to be a conflict, please backport manually. Here are approximate instructions:

1. Checkout backport branch and update it.

git checkout v7.1.x
git pull

2. Cherry pick the first parent branch of the this PR on top of the older branch:

git cherry-pick -x -m1 7ee167b45c738acaba61ee7ba8df2141d5848069

3. You will likely have some merge/cherry-pick conflict here, fix them and commit:

git commit -am 'Backport PR #18381: TST: Add Sersic2D to NON_FINITE_LM_MODELS'

4. Push to a named branch:

git push YOURFORK v7.1.x:auto-backport-of-pr-18381-on-v7.1.x

5. Create a PR against branch v7.1.x, I would have named this PR:

"Backport PR #18381 on branch v7.1.x (TST: Add Sersic2D to NON_FINITE_LM_MODELS)"

And apply the correct labels and milestones.

Congratulations — you did some good work! Hopefully your backport PR will be tested by the continuous integration and merged soon!

Remember to remove the Still Needs Manual Backport label once the PR gets merged.

If these instructions are inaccurate, feel free to suggest an improvement.

I'll backport this manually

backport at #18382

Thanks, all!