Update README to reflect Python 3.10+ requirement

The package now requires Python 3.10+ due to security fixes for
langchain-core>=1.2.11 and langsmith>=0.6.3 dependencies.

Updated:
- Badge: Python 3.9+ → Python 3.10+
- Requirements section: Python 3.9+ → Python 3.10+

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: prathamesh-sonpatki

README.md

@@ -3,7 +3,7 @@
 > OpenTelemetry extension for LLM observability: track conversations, workflows, and costs
 
 [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT)
-[![Python 3.9+](https://img.shields.io/badge/python-3.9+-blue.svg)](https://www.python.org/downloads/)
+[![Python 3.10+](https://img.shields.io/badge/python-3.10+-blue.svg)](https://www.python.org/downloads/)
 
 ## Overview
 
@@ -67,7 +67,7 @@ pip install last9-genai[otlp]
 ```
 
 **Requirements:**
-- Python 3.9+
+- Python 3.10+
 - `opentelemetry-api>=1.20.0`
 - `opentelemetry-sdk>=1.20.0`