fix SupportsQueryableEncryptionTests after removal of MongoDB 6.0

Author: timgraham

tests/backend_/test_features.py

@@ -50,8 +50,9 @@ class SupportsQueryableEncryptionTests(TestCase):
     def setUp(self):
         # Clear the cached property.
         connection.features.__dict__.pop("supports_queryable_encryption", None)
-        # Must initialize the feature before patching it.
+        # Must initialize cached properties before patching them.
         connection.features._supports_transactions  # noqa: B018
+        connection.features.mongodb_version  # noqa: B018
 
     def tearDown(self):
         del connection.features.supports_queryable_encryption