model update API for checkpointing

[Borda]

What does this PR do?

aligning with the next version... for Lightning-AI/LitModels#94

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📚 Documentation preview 📚: https://pytorch-lightning--20721.org.readthedocs.build/en/20721/

[github-actions]

⚡ Required checks status: All passing 🟢

Groups summary

🟢 pytorch_lightning: Tests workflow

Check ID	Status
pl-cpu-guardian	success	✅

These checks are required after the changes to src/lightning/pytorch/trainer/connectors/callback_connector.py.

🟢 pytorch_lightning: Azure GPU

Check ID	Status
pytorch-lightning (GPUs) (testing Lightning | latest)	success	✅
pytorch-lightning (GPUs) (testing PyTorch | latest)	success	✅

These checks are required after the changes to src/lightning/pytorch/trainer/connectors/callback_connector.py.

🟢 pytorch_lightning: Benchmarks

Check ID	Status
lightning.Benchmarks	success	✅

These checks are required after the changes to src/lightning/pytorch/trainer/connectors/callback_connector.py.

🟢 pytorch_lightning: Docs

Check ID	Status
docs-make (pytorch, doctest)	success	✅
docs-make (pytorch, html)	success	✅

These checks are required after the changes to src/lightning/pytorch/trainer/connectors/callback_connector.py.

🟢 mypy

Check ID	Status
mypy	success	✅

These checks are required after the changes to src/lightning/pytorch/trainer/connectors/callback_connector.py.

🟢 install

Check ID	Status
install-pkg-guardian	success	✅

These checks are required after the changes to src/lightning/pytorch/trainer/connectors/callback_connector.py.

---

Thank you for your contribution! 💜

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[codecov]

Codecov Report

Attention: Patch coverage is 66.66667% with 1 line in your changes missing coverage. Please review.

Project coverage is 79%. Comparing base (d57c2a3) to head (510d307).
Report is 136 commits behind head on master.

✅ All tests successful. No failed tests found.

❗ There is a different number of reports uploaded between BASE (d57c2a3) and HEAD (510d307). Click for more details.

HEAD has 363 uploads less than BASE

Flag	BASE (d57c2a3)	HEAD (510d307)
cpu	108	27
python3.10	24	6
lightning_fabric	27	0
pytest	58	0
python	12	3
python3.12	12	3
python3.12.7	36	9
lightning	61	15
python3.11	24	6
gpu	4	0
pytorch2.1	12	6
pytorch_lightning	24	12
pytest-full	54	27
pytorch2.2.2	6	3
pytorch2.3	6	3
pytorch2.5	6	3
pytorch2.4.1	6	3
pytorch2.7	6	3
pytorch2.6	6	3
pytorch2.5.1	6	3

Additional details and impacted files

@@            Coverage Diff            @@
##           master   #20721     +/-   ##
=========================================
- Coverage      87%      79%     -8%     
=========================================
  Files         268      265      -3     
  Lines       23449    23394     -55     
=========================================
- Hits        20389    18386   -2003     
- Misses       3060     5008   +1948