ci: remove unnecessary Python setup from macOS CI

[luoliwoshang]

Summary

Fixes #585

Remove unnecessary Python 3.12 setup from macOS CI that was causing demo tests to fail with exit code 1.

Changes

.github/actions/setup-llcppg/action.yml

• Remove brew install python@3.12 || true
• Remove brew link --overwrite python@3.12

.github/workflows/go.yml

• Remove entire Python symlink setup block (12 lines)
• Simplify "Test demos" step to directly run the test script

Why This Works

The original code attempted to create a symlink for python3-embed pointing to python-3.12-embed for PyTorch compatibility. However:

1. The project has no _pydemo directory
2. Only _demo/cjsondemo exists, which doesn't require Python
3. The pkg-config --variable=libdir python-3.12-embed command was failing because Python 3.12 wasn't installed
4. This caused the entire "Test demos" step to exit early with code 1

Benefits

• ✅ Fixes macOS-latest CI failures
• ✅ Simplifies CI configuration
• ✅ Faster build times (no Python installation)
• ✅ Removes unused dependencies

Test Plan

• Verify CI passes on macOS-latest
• Confirm demo tests run successfully
• Check that cjsondemo still works correctly

🤖 Generated with Claude Code

[gemini-code-assist]

Summary of Changes

Hello @luoliwoshang, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request aims to stabilize the macOS CI pipeline by rectifying a version mismatch issue. The demo tests, which rely on Python 3.12 for embedding, were failing because the macOS-latest environment defaulted to Python 3.13, causing critical pkg-config commands to fail. The change introduces an explicit installation of Python 3.12 during the CI setup, thereby enabling the demo tests to execute as intended and ensuring the necessary symlinks are correctly established.

Highlights

• CI Fix: Resolves macOS-latest CI failures in demo tests by ensuring Python 3.12 is available.
• Dependency Management: Addresses the pkg-config --variable=libdir python-3.12-embed command failure by explicitly installing the required Python version.
• Symlink Creation: Ensures the test_demo.sh script can successfully create the python3-embed symlink.

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[gemini-code-assist]

Code Review

This pull request correctly addresses the macOS CI failure by installing python@3.12. The change is simple and effective. I've added one suggestion to consolidate two of the brew install commands for better conciseness. Overall, this is a good fix.

[gemini-code-assist]

You can combine these two brew install commands into one for conciseness and to reduce the number of shell commands executed.

      brew install zlib python@3.12 # for llgo test & pydemo tests

[fennoai]

Overall Assessment: Approved with minor documentation suggestion

This PR correctly addresses the macOS CI failure by installing Python 3.12. The change is minimal, well-placed, and solves the immediate issue. I've left one inline comment suggesting a more accurate comment to better reflect the actual use case (python-3.12-embed pkg-config support rather than just "pydemo tests").

Note: The _pydemo directory doesn't exist yet, so this is a forward-looking change. The installation adds ~40-60 seconds to macOS CI runs.

[fennoai]

The comment "for pydemo tests" is somewhat misleading. The actual purpose is to provide the python-3.12-embed pkg-config module, as shown in go.yml lines 79-88 where it's used to create a python3-embed symlink workaround for PyTorch compatibility.

Consider updating to be more specific:

Suggested change

	brew install python@3.12 # for pydemo tests
	brew install python@3.12 # required for python-3.12-embed pkg-config module

This better reflects the actual use case and aligns with the TODO comment in go.yml explaining the PyTorch/Python 3.13 compatibility issue.

[fennoai]

Overall Assessment: Approved with minor documentation suggestion

This PR correctly addresses the macOS CI failure by installing Python 3.12. The change is minimal, well-placed, and solves the immediate issue. I've left one inline comment suggesting a more accurate comment to better reflect the actual use case (python-3.12-embed pkg-config support rather than just "pydemo tests").

Note: The _pydemo directory doesn't exist yet, so this is a forward-looking change. The installation adds ~40-60 seconds to macOS CI runs.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.74%. Comparing base (7955d98) to head (b8aaa95).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #584      +/-   ##
==========================================
+ Coverage   84.19%   84.74%   +0.54%     
==========================================
  Files          27       27              
  Lines        2746     2314     -432     
==========================================
- Hits         2312     1961     -351     
+ Misses        391      310      -81     
  Partials       43       43              

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