feat: add support for Python 3.10 (#284)

Fix new deprecation warning for 'threading.Condition.notifyAll'.
diff --git a/noxfile.py b/noxfile.py
index 6478bfd..617dc58 100644
--- a/noxfile.py
+++ b/noxfile.py
@@ -121,7 +121,7 @@
         session.run(*pytest_args)
 
 
[email protected](python=["3.6", "3.7", "3.8", "3.9"])
[email protected](python=["3.6", "3.7", "3.8", "3.9", "3.10"])
 def unit(session):
     """Run the unit test suite."""
     default(session)