Add Python 3.13 Support

🎯 Overview

This PR adds Python 3.13 support to aaz-dev-tools, addressing azure-cli issue #29640.

🔧 Changes Made

• Updated package metadata to declare Python 3.13 compatibility in setup.py classifiers
• Upgraded lxml dependency from >=4.9.0 to >=5.0.0 for Python 3.13 compatibility
• Updated documentation to reflect Python 3.8-3.13 support range
• Enhanced extension templates to include Python 3.10-3.13 in generated CLI extensions
• Updated test fixtures to match the new template changes

📋 Files Modified

• setup.py - Added Python 3.11, 3.12, 3.13 classifiers
• requirements.txt - Bumped lxml to >=5.0.0
• docs/pages/usage/setup_and_run.md - Updated compatibility documentation
• src/aaz_dev/cli/templates/extension/setup.py.j2 - Enhanced extension template
• Test output files to reflect template updates

✅ Testing

Comprehensive compatibility testing has been performed across:

• Operating Systems: Ubuntu, macOS, Windows
• Python Versions: 3.8, 3.9, 3.10, 3.11, 3.12, 3.13
• Results: View test runs

All tests pass successfully, confirming that the package builds and installs correctly on Python 3.13 across all supported platforms.

🔗 Related Issues

Addresses: Azure/azure-cli#29640