CI: adjust doctests for lightning.pytorch

[awaelchli]

What does this PR do?

Same as #15457 but for doctest. See the failing run https://github.com/Lightning-AI/lightning/actions/runs/3373154980/jobs/5597446136 in PR #15301

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Did you have fun?

I made sure I had fun coding 🙃

cc @carmocca @akihironitta @Borda

[awaelchli]

Why did you merge this :(I disabled auto merge. It is not working, as you can see I was testing it here: #15301

[Borda]

Why did you merge this :(I disabled auto merge. It is not working, as you can see I was testing it here: #15301

it was my bad I checked and seems fine, did not realize the names as the GH's diff was too small... my had :(