Fixed setup.cfg

Author: Sylvain MARIE

setup.cfg

@@ -27,6 +27,7 @@ classifiers =
     Programming Language :: Python :: 3.6
     Programming Language :: Python :: 3.7
     Programming Language :: Python :: 3.8
+    Programming Language :: Python :: 3.9
     Framework :: Pytest
 
 [options]
@@ -144,6 +145,6 @@ exclude =
     tests
     noxfile.py
     setup.py
-    pytest_cases/tests
+    tests
     _version.py
-    pytest_cases/_version.py
+    src/_version.py