fix: update Python version requirements to 3.9-3.13

[noppanut15]

🎯 Purpose of this PR

Clarify and enforce the supported Python version range to prevent users from attempting to use depthviz with Python 3.14 or higher, where underlying dependencies may not yet be compatible.

🛠️ Changes Made

• Documentation update: 📝
  • Updated README.md to specify "Python 3.9 to 3.13" instead of "Python 3.9 or higher"
• Code refactor: 🛠️
  • Updated pyproject.toml Python constraint from ^3.9 to >=3.9,<3.14 to enforce version limits at installation time
  • Added Python 3.13 to CI test matrix in .github/workflows/deploy.yaml to ensure compatibility testing across all supported versions

📸 Screenshots or GIF (if applicable)

N/A - Documentation and configuration changes only.

📜 How to Test

1. Verify that the package can be installed on Python 3.9-3.13:

   # Test with different Python versions
   python3.9 -m pip install depthviz
   python3.13 -m pip install depthviz

2. Verify that installation is blocked on Python 3.14+ (when available):

   python3.14 -m pip install depthviz
   # Should fail with a Python version compatibility error

3. Check that CI tests run successfully for all Python versions (3.9, 3.10, 3.11, 3.12, 3.13)

✅ Checklist Before Merge

• Code follows the project's style guidelines.
• PR is based on the main branch and is up to date.
• All tests pass.
• Documentation is updated (if applicable).
• PR title follows Conventional Commits.
• I have read the CONTRIBUTING.md guidelines.

💬 Additional Notes (optional)

This change ensures users won't encounter cryptic errors when trying to use depthviz with Python 3.14+. The version constraint will need to be updated in the future once all underlying dependencies officially support Python 3.14 or higher.