Infra: Link target release to release PEP in PEP 0

[BHUVANSH855]

Summary

This change links Python version entries in PEP 0 to their corresponding release schedule PEPs.

Specifically, it:

• Builds a mapping from Python versions to release schedule PEP numbers using release-topic metadata.
• Emits :pep: references for Python version entries when a matching release schedule PEP exists.
• Falls back to plain text when no matching release schedule PEP is available.
• Adds a regression test covering the new linking behavior.

Testing

python -m pytest
python build.py

Results:

• 532 passed, 2 xfailed
• Documentation build succeeded

Issue

Closes #4379

[read-the-docs-community]

Documentation build overview

📚 pep-previews | 🛠️ Build #33766193 | 📁 Comparing 23fee33 against latest (9bb3132)

  🔍 Preview build  

7 files changed · ± 7 modified

± Modified

• index.html
• numerical/index.html
• pep-0000/index.html
• pep-0764/index.html
• topic/packaging/index.html
• topic/release/index.html
• topic/typing/index.html

[hugovk]

Please also check topic pages such as https://pep-previews--5058.org.readthedocs.build/topic/packaging/, they don't have linked versions.

Is it worth also linking on the release topic page? https://pep-previews--5058.org.readthedocs.build/topic/release/

---

Some with multiple versions don't get linked:

(That "2.6, 3.0" is a link to the joint 2.6/3.0 PEP.)

Add tests to include cases like "2.6, 3.0", "2.7, 3.1" and "2.4, 2.5, 2.6".

[BHUVANSH855]

Thanks! I've updated the topic pages to use the same release_peps mapping as PEP 0 and the numerical index, so the Python version links are now generated there as well.

I've also added regression tests covering the historical multi-version cases you mentioned:

• 2.6, 3.0
• 2.7, 3.1
• 2.4, 2.5, 2.6

I've verified the changes with python build.py and the full test suite (535 passed, 2 xfailed).