Update lightning version to v1.2

[kaushikb11]

What does this PR do?

Fixes #132

Before submitting

• Was this discussed/approved via a Github issue? (no need for typos and docs improvements)
• Did you read the contributor guideline, Pull Request section?
• Did you make sure your PR does only one thing, instead of bundling different changes together?
• Did you make sure to update the documentation with your changes?
• Did you write any new necessary tests? [not needed for typos/docs]
• Did you verify new and existing tests pass locally with your changes?
• If you made a notable change (that affects users), did you update the CHANGELOG?

PR review

• Is this pull request ready for review? (if not, please submit in draft mode)

Anyone in the community is free to review the PR once the tests have passed.
If we didn't discuss your PR in Github issues there's a high chance it will not be merged.

Did you have fun?

Make sure you had fun coding 🙃

[codecov]

Codecov Report

Merging #133 (068ad2c) into master (b918adb) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #133   +/-   ##
=======================================
  Coverage   87.04%   87.04%           
=======================================
  Files          49       49           
  Lines        1590     1590           
=======================================
  Hits         1384     1384           
  Misses        206      206           

Flag	Coverage Δ
unittests	87.04% <100.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
flash/core/finetuning.py	88.67% <100.00%> (ø)
flash/vision/detection/finetuning.py	100.00% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update b918adb...068ad2c. Read the comment docs.

[Borda]

@carmocca @kaushikb11 can we continue the predict talk here 🐰

[Borda]

@kaushikb11 any progress here? it would be nice to have Flash release working fine with mainstream PL (not the hack RC we have now) cc: @aribornstein

[kaushikb11]

@Borda Let me look at the failing tests today, weren't failing before.

[kaushikb11]

@Borda Had a talk with Carlos. We can't point to lightning 1.2 unless #141 PR is in, and there are other changes required in Lightning as well.

[carmocca]

Also #130. And updating the Lightning Trainer to call model.predict_step instead of model.predict
cc: @justusschock

[edgarriba]

IDK about the finetunning functions but the change of requirements is needed to unbock other branches like datapipeline. If not inconvenient I'd merge. /cc @kaushikb11 @tchaton

[Borda]

@kaushikb11 there are some PL related error, such as misconfiguration, mind have a look

[kaushikb11]

@Borda Sure!

[kaushikb11]

One Unblocking PR Lightning-AI/pytorch-lightning#6541

[Borda]

One Unblocking PR PyTorchLightning/pytorch-lightning#6541

which means we would need to sen min version to 1.2.4 or higher...