Update README.md

Author: rllin

README.md

@@ -6,7 +6,7 @@ The Labelbox Python API offers a simple, user-friendly way to interact with the
 
 ## Requirements
 
-* Use Python 3.6 or 3.7.
+* Use Python 3.7 or 3.8.
 * Create an account by visiting http://app.labelbox.com/.
 * [Generate an API key](https://labelbox.com/docs/api/api-keys).