Prepare Lightning 2.5.0 release

[lantiga]

What does this PR do?

Bumps the version of the package to 2.5.0 for the release, updates the changelog, and versions in issue template.

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📚 Documentation preview 📚: https://pytorch-lightning--20505.org.readthedocs.build/en/20505/

cc @justusschock @awaelchli

[github-actions]

⚡ Required checks status: All passing 🟢

Groups summary

🟢 mypy

Check ID	Status
mypy	success	✅

These checks are required after the changes to src/version.info.

🟢 install

Check ID	Status
install-pkg (ubuntu-22.04, fabric, 3.9)	success	✅
install-pkg (ubuntu-22.04, fabric, 3.11)	success	✅
install-pkg (ubuntu-22.04, pytorch, 3.9)	success	✅
install-pkg (ubuntu-22.04, pytorch, 3.11)	success	✅
install-pkg (ubuntu-22.04, lightning, 3.9)	success	✅
install-pkg (ubuntu-22.04, lightning, 3.11)	success	✅
install-pkg (ubuntu-22.04, notset, 3.9)	success	✅
install-pkg (ubuntu-22.04, notset, 3.11)	success	✅
install-pkg (macOS-14, fabric, 3.9)	success	✅
install-pkg (macOS-14, fabric, 3.11)	success	✅
install-pkg (macOS-14, pytorch, 3.9)	success	✅
install-pkg (macOS-14, pytorch, 3.11)	success	✅
install-pkg (macOS-14, lightning, 3.9)	success	✅
install-pkg (macOS-14, lightning, 3.11)	success	✅
install-pkg (macOS-14, notset, 3.9)	success	✅
install-pkg (macOS-14, notset, 3.11)	success	✅
install-pkg (windows-2022, fabric, 3.9)	success	✅
install-pkg (windows-2022, fabric, 3.11)	success	✅
install-pkg (windows-2022, pytorch, 3.9)	success	✅
install-pkg (windows-2022, pytorch, 3.11)	success	✅
install-pkg (windows-2022, lightning, 3.9)	success	✅
install-pkg (windows-2022, lightning, 3.11)	success	✅
install-pkg (windows-2022, notset, 3.9)	success	✅
install-pkg (windows-2022, notset, 3.11)	success	✅

These checks are required after the changes to src/version.info.

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Thank you for your contribution! 💜

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