Temporarily pin Python at 3.12.7 to avoid jsonargparse issue in CI

[lantiga]

What does this PR do?

A change in a private method in the Python standard library causes jsonargparse to error out with Python >=3.12.8
See: omni-us/jsonargparse#641

This PR temporarily pins Python 3.12 to 3.12.7 in CI to allow tests to pass while jsonargparse gets a fix.

---

📚 Documentation preview 📚: https://pytorch-lightning--20476.org.readthedocs.build/en/20476/

[github-actions]

🌩️ Required checks status: Pending 🟡

Groups summary

🟡 pytorch_lightning: Tests workflow

Check ID	Status
pl-cpu (macOS-14, lightning, 3.9, 2.1, oldest)	success	✅
pl-cpu (macOS-14, lightning, 3.10, 2.1)	success	✅
pl-cpu (macOS-14, lightning, 3.11, 2.2.2)	success	✅
pl-cpu (macOS-14, lightning, 3.11, 2.3)	success	✅
pl-cpu (macOS-14, lightning, 3.12, 2.4.1)	no_status	❓
pl-cpu (macOS-14, lightning, 3.12, 2.5.1)	no_status	❓
pl-cpu (ubuntu-20.04, lightning, 3.9, 2.1, oldest)	success	✅
pl-cpu (ubuntu-20.04, lightning, 3.10, 2.1)	success	✅
pl-cpu (ubuntu-20.04, lightning, 3.11, 2.2.2)	success	✅
pl-cpu (ubuntu-20.04, lightning, 3.11, 2.3)	success	✅
pl-cpu (ubuntu-22.04, lightning, 3.12, 2.4.1)	no_status	❓
pl-cpu (ubuntu-22.04, lightning, 3.12, 2.5.1)	no_status	❓
pl-cpu (windows-2022, lightning, 3.9, 2.1, oldest)	success	✅
pl-cpu (windows-2022, lightning, 3.10, 2.1)	success	✅
pl-cpu (windows-2022, lightning, 3.11, 2.2.2)	success	✅
pl-cpu (windows-2022, lightning, 3.11, 2.3)	success	✅
pl-cpu (windows-2022, lightning, 3.12, 2.4.1)	no_status	❓
pl-cpu (windows-2022, lightning, 3.12, 2.5.1)	no_status	❓
pl-cpu (macOS-14, pytorch, 3.9, 2.1)	success	✅
pl-cpu (ubuntu-20.04, pytorch, 3.9, 2.1)	success	✅
pl-cpu (windows-2022, pytorch, 3.9, 2.1)	success	✅
pl-cpu (macOS-14, pytorch, 3.12, 2.5.1)	no_status	❓
pl-cpu (ubuntu-22.04, pytorch, 3.12, 2.5.1)	no_status	❓
pl-cpu (windows-2022, pytorch, 3.12, 2.5.1)	no_status	❓

These checks are required after the changes to .github/workflows/ci-tests-pytorch.yml.

🟡 lightning_fabric: CPU workflow

Check ID	Status
fabric-cpu (macOS-14, lightning, 3.9, 2.1, oldest)	success	✅
fabric-cpu (macOS-14, lightning, 3.10, 2.1)	success	✅
fabric-cpu (macOS-14, lightning, 3.11, 2.2.2)	success	✅
fabric-cpu (macOS-14, lightning, 3.11, 2.3)	success	✅
fabric-cpu (macOS-14, lightning, 3.12, 2.4.1)	no_status	❓
fabric-cpu (macOS-14, lightning, 3.12, 2.5.1)	no_status	❓
fabric-cpu (ubuntu-20.04, lightning, 3.9, 2.1, oldest)	success	✅
fabric-cpu (ubuntu-20.04, lightning, 3.10, 2.1)	success	✅
fabric-cpu (ubuntu-20.04, lightning, 3.11, 2.2.2)	success	✅
fabric-cpu (ubuntu-20.04, lightning, 3.11, 2.3)	success	✅
fabric-cpu (ubuntu-22.04, lightning, 3.12, 2.4.1)	no_status	❓
fabric-cpu (ubuntu-22.04, lightning, 3.12, 2.5.1)	no_status	❓
fabric-cpu (windows-2022, lightning, 3.9, 2.1, oldest)	success	✅
fabric-cpu (windows-2022, lightning, 3.10, 2.1)	success	✅
fabric-cpu (windows-2022, lightning, 3.11, 2.2.2)	success	✅
fabric-cpu (windows-2022, lightning, 3.11, 2.3)	success	✅
fabric-cpu (windows-2022, lightning, 3.12, 2.4.1)	no_status	❓
fabric-cpu (windows-2022, lightning, 3.12, 2.5.1)	no_status	❓
fabric-cpu (macOS-14, fabric, 3.9, 2.1)	success	✅
fabric-cpu (ubuntu-20.04, fabric, 3.9, 2.1)	success	✅
fabric-cpu (windows-2022, fabric, 3.9, 2.1)	success	✅
fabric-cpu (macOS-14, fabric, 3.12, 2.5.1)	no_status	❓
fabric-cpu (ubuntu-22.04, fabric, 3.12, 2.5.1)	no_status	❓
fabric-cpu (windows-2022, fabric, 3.12, 2.5.1)	no_status	❓

These checks are required after the changes to .github/workflows/ci-tests-fabric.yml.

---

Thank you for your contribution! 💜

Note
This comment is automatically generated and updates for 60 minutes every 180 seconds. If you have any other questions, contact carmocca for help.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87%. Comparing base (be608fa) to head (7cb7563).
Report is 47 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff            @@
##           master   #20476    +/-   ##
========================================
- Coverage      88%      87%    -1%     
========================================
  Files         267      267            
  Lines       23276    23276            
========================================
- Hits        20383    20137   -246     
- Misses       2893     3139   +246     

🚀 New features to boost your workflow:

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