fix: update Python version requirement to 3.10+

BREAKING CHANGE: Python 3.8 and 3.9 are no longer supported

- MCP package requires Python >=3.10 (all versions from 0.9.1 to 1.9.3)
- Update setup.py to require Python >=3.10
- Update GitHub Actions to only test Python 3.10, 3.11, and 3.12
- Update README.md with correct Python version requirement
- Remove typing-extensions dependency (not needed for Python 3.10+)
- Remove Python 3.8/3.9 from classifiers

This resolves all GitHub Actions failures for Python 3.8/3.9 tests.

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

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

README.md

@@ -15,7 +15,7 @@ This server acts as a developer assistant that augments Claude Code when you nee
 
 Before you begin, ensure you have the following:
 
-1. **Python:** Python 3.8 or newer. Check your version with `python3 --version`
+1. **Python:** Python 3.10 or newer. Check your version with `python3 --version`
 2. **Claude Desktop:** A working installation of Claude Desktop and the `claude` command-line tool
 3. **Gemini API Key:** An active API key from [Google AI Studio](https://aistudio.google.com/app/apikey)
    - Ensure your key is enabled for the `gemini-2.5-pro-preview` model