Fix collection test

- collections.abc was added in 3.3 collections.Hashable removed in 3.10
diff --git a/test/py/TestFrozen.py b/test/py/TestFrozen.py
index f859398..5f685d4 100755
--- a/test/py/TestFrozen.py
+++ b/test/py/TestFrozen.py
@@ -25,7 +25,7 @@
 from thrift.Thrift import TFrozenDict
 from thrift.transport import TTransport
 from thrift.protocol import TBinaryProtocol, TCompactProtocol
-import collections
+from collections.abc import Hashable
 import unittest
 
 
@@ -40,9 +40,9 @@
 
     def test_dict_is_hashable_only_after_frozen(self):
         d0 = {}
-        self.assertFalse(isinstance(d0, collections.Hashable))
+        self.assertFalse(isinstance(d0, Hashable))
         d1 = TFrozenDict(d0)
-        self.assertTrue(isinstance(d1, collections.Hashable))
+        self.assertTrue(isinstance(d1, Hashable))
 
     def test_struct_with_collection_fields(self):
         pass