update readme

Author: bmoscon

README.md

@@ -1,7 +1,7 @@
 # Orderbook
 
 [![License](https://img.shields.io/badge/license-GLPv3-blue.svg)](LICENSE)
-![Python](https://img.shields.io/badge/Python-3.8+-green.svg)
+![Python](https://img.shields.io/badge/Python-3.11+-green.svg)
 [![PyPi](https://img.shields.io/badge/PyPi-order--book-brightgreen)](https://pypi.python.org/pypi/order-book)
 ![coverage-lines](https://img.shields.io/badge/coverage%3A%20lines-84.6%25-blue)
 ![coverage-functions](https://img.shields.io/badge/coverage%3A%20functions-100%25-blue)