feat(python): add Python 3.12 support

[dganesh05]

• Updated setuptools version in pyproject.toml to 68.2.2.
• Updated numpy version in pyproject.toml to >=1.26.0.
• Added support for Python 3.12 in various GitHub workflows.
• Modified database query execution to use engine.connect() instead of pd.read_sql_query.
• Updated .gitignore to include .venv312 and .cursor directories.
• Added peerDependencies for eslint in package-lock.json.

feat(python): add Python 3.12 support

SUMMARY

This PR adds official support for Python 3.12 to Apache Superset. The changes ensure compatibility with Python 3.12 while maintaining backward compatibility with Python 3.10 and 3.11.

Key changes:

1. Dependency updates: Updated setuptools to 68.2.2 and numpy to >=1.26.0 to ensure Python 3.12 compatibility
2. Python classifier: Added "Programming Language :: Python :: 3.12" to pyproject.toml classifiers
3. CI/CD integration: Updated GitHub Actions workflows to include Python 3.12 in the test matrix:
   • superset-python-unittest.yml: Added "next" (maps to Python 3.12) to the test matrix
   • pre-commit.yml: Already includes "next" in the matrix
   • setup-backend/action.yml: Maps "next" to Python 3.12
4. Pandas API modernization: Replaced deprecated pd.read_sql_query() calls with engine.connect() context manager pattern in:
   • superset/models/helpers.py
   • superset/connectors/sqla/models.py
5. Development environment: Updated .gitignore to exclude Python 3.12 virtual environment (.venv312) and .cursor directory

Rationale:

• Python 3.12 is the latest stable release and provides performance improvements and new features
• The pandas API changes ensure compatibility with future pandas versions that may deprecate read_sql_query()
• Using engine.connect() is the recommended SQLAlchemy pattern and provides better resource management

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

N/A - This is a backend compatibility change with no UI impact.

TESTING INSTRUCTIONS

1. Create a Python 3.12 virtual environment:

   python3.12 -m venv .venv312
   source .venv312/bin/activate

2. Install Superset:

   pip install -r requirements/base.txt
   pip install -e .

3. Run the comprehensive test script:

   bash comprehensive_test.sh

4. Verify all tests pass:

   • All acceptance criteria should pass (9/9)
   • No dependency conflicts (pip check should pass)
   • Unit tests should run successfully on Python 3.12

5. Manual verification:

   • Start Superset: superset run -p 8088
   • Verify the application starts without errors
   • Create a chart that queries a database
   • Verify the chart renders successfully without pandas-related errors

6. CI/CD verification:

   • Check that GitHub Actions workflows run successfully with Python 3.12
   • Verify the "next" Python version in the test matrix maps to 3.12

ADDITIONAL INFORMATION

• Has associated issue: Fixes Issue #6 - Table Chart "Sort Descending" control appears when no sort metric is selected and has a confusing UI location #19
• Required feature flags:
• Changes UI
• Includes DB Migration (follow approval process in SIP-59)
  • Migration is atomic, supports rollback & is backwards-compatible
  • Confirm DB migration upgrade and downgrade tested
  • Runtime estimates and downtime expectations provided
• Introduces new feature or API
• Removes existing feature or API