Update supported version in README (#964)

Co-authored-by: Thomas Hervé <[email protected]>

Author: skarimo

README.md

@@ -4,7 +4,7 @@ This repository contains a Python API client for the [Datadog API](https://docs.
 
 ## Requirements
 
-Building and using the API client library requires [Python 3.6+](https://www.python.org/downloads/).
+Building and using the API client library requires [Python 3.7+](https://www.python.org/downloads/).
 
 ## Installation