Pin selenium >= 4.0.0.b4 which fixes a regression with file uploads for functional tests.

Author: stevepiercy

setup.py

@@ -73,7 +73,7 @@ def readfile(name):
 
 # Selenium 4.0 does not work on Python 3.6.
 if PY37MIN:
-    functional_testing_extras.extend(["selenium >= 4.0a, < 4.0.0.b1"])
+    functional_testing_extras.extend(["selenium >= 4.0.0.b4"])
 else:
     functional_testing_extras.extend(["selenium >= 3.0, < 4.0"])