chore: add .python-version to templates missing it

[AshSgDe29071999]

Summary

Most templates lacked .python-version, so pyenv/uv would not pin Python when entering a scaffolded project.

Changes

• Add .python-version aligned with each template's requires-python (default 3.12)

Closes#153

Summary by CodeRabbit

• Chores
  • Standardized the Python version to 3.12 across the Celery worker, CLI, Django API, FastAPI, and MLOps starter templates.
  • New projects created from these templates now use a consistent Python runtime by default.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: df8f0047-9844-47cf-ba47-9cb01dd9e87c

📥 Commits

Reviewing files that changed from the base of the PR and between 6986f9b and ab27ce4.

📒 Files selected for processing (5)

• templates/celery-worker/.python-version
• templates/cli-starter/.python-version
• templates/django-api/.python-version
• templates/fastapi-starter/.python-version
• templates/mlops-sklearn-starter/.python-version

---

📝 Walkthrough

Walkthrough

Added .python-version files containing Python 3.12 to five templates: Celery, CLI, Django, FastAPI, and MLOps scikit-learn.

Changes

Python version pins

Layer / File(s)	Summary
Add template Python version files templates/*/.python-version	Added .python-version files containing 3.12 to five templates.

Estimated code review effort: 1 (Trivial) | ~2 minutes

Possibly related PRs

• Create-Python-App/cpa-templates#154: Adds the same Python 3.12 .python-version files to the same five templates.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly identifies the addition of .python-version files to templates missing them.
Linked Issues check	✅ Passed	The PR adds 3.12 .python-version files to all five templates required by issue #153.
Out of Scope Changes check	✅ Passed	All changes directly support issue #153, with no unrelated modifications identified.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}

[ulises-jeremias]

Thanks @AshSgDe29071999 — closing as duplicate of #159 (same scope #152.python-version). #159 already combines #152+#153 canonically. Thanks for the contribution!