using python3.10 instead of python3.9

tox.ini

 [tox]
-envlist = py39
+envlist = py310
 requires = setuptools >= 40.0.0
 
 [testenv]
@@ -8,7 +8,7 @@ deps =
 commands = pytest --junitxml=report.xml
 
 [testenv:docs]
-basepython = python3.9
+basepython = python3.10
 deps =
   sphinx