Downgrade to simplejson 3.17.2. (#123)

* Downgrade to simplejson 3.17.2.

* Fix test formatting.

Author: briensea

Diff for: requirements/base.txt

@@ -1 +1 @@
-simplejson==3.17.6
+simplejson==3.17.2

Diff for: tests/test_lambda_runtime_marshaller.py

@@ -42,4 +42,6 @@ def test_to_json_unicode_encoding(self):
         response = to_json({"price": "£1.00"})
         self.assertEqual('{"price": "£1.00"}', response)
         self.assertNotEqual('{"price": "\\u00a31.00"}', response)
-        self.assertEqual(19, len(response.encode('utf-8')))  # would be 23 bytes if a unicode escape was returned
+        self.assertEqual(
+            19, len(response.encode("utf-8"))
+        )  # would be 23 bytes if a unicode escape was returned