fix: ensure virtual environment uses correct Python version in CI

Fix issue where uv venv was creating virtual environments with a different
Python version than specified in the matrix, causing wheel compatibility
errors. The problem occurred when the system had multiple Python versions
and uv venv defaulted to a different version than intended.

Changes:
- Add --python ${{ matrix.python }} flag to uv venv command
- Ensures virtual environment matches the matrix-specified Python version
- Fixes "The wheel is compatible with CPython 3.X but you're using CPython 3.Y" errors

This ensures wheel installation selects and installs the correctly built
wheels that match the runtime Python version.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

.github/workflows/build-reusable.yml

@@ -238,8 +238,8 @@ jobs:
 
       - name: Install built packages for testing
         run: |
-          # Create a virtual environment
-          uv venv
+          # Create a virtual environment with the correct Python version
+          uv venv --python ${{ matrix.python }}
           source .venv/bin/activate || source .venv/Scripts/activate
 
           # Install the built wheels directly without checking PyPI