enable mypy_test for python 3.10 (#5341)

* enable mypy_test for python 3.10

* avoid collections.Mapping and collections.MutableMapping, import from typing

tests/mypy_test.py

@@ -172,7 +172,7 @@ def main():
         print("Cannot import mypy. Did you install it?")
         sys.exit(1)
 
-    versions = [(3, 9), (3, 8), (3, 7), (3, 6), (2, 7)]
+    versions = [(3, 10), (3, 9), (3, 8), (3, 7), (3, 6), (2, 7)]
     if args.python_version:
         versions = [v for v in versions if any(("%d.%d" % v).startswith(av) for av in args.python_version)]
         if not versions: