Merge pull request #36 from antoinedemathelin/master

docs: add python 39

Author: antoinedemathelin

README.md

@@ -2,7 +2,7 @@
 
 [![PyPI version](https://badge.fury.io/py/adapt.svg)](https://pypi.org/project/adapt)
 [![Build Status](https://github.com/adapt-python/adapt/workflows/build/badge.svg)](https://github.com/adapt-python/adapt/actions)
-[![Python Version](https://img.shields.io/badge/python-3.6%20|%203.7%20|%203.8-blue)](https://img.shields.io/badge/python-3.5%20|%203.6%20|%203.7-blue)
+[![Python Version](https://img.shields.io/badge/python-3.6%20|%203.7%20|%203.8|%203.9-blue)](https://img.shields.io/badge/python-3.6%20|%203.7%20|%203.8|%203.9-blue)
 [![Codecov Status](https://codecov.io/gh/adapt-python/adapt/branch/master/graph/badge.svg?token=IWQXMYGY2Q)](https://codecov.io/gh/adapt-python/adapt)
 
 **A**wesome **D**omain **A**daptation **P**ython **T**oolbox