<!-- Love localstack? Please consider supporting our collective:
👉  https://opencollective.com/localstack/donate -->

Under utils/common.py, 

TIMESTAMP_FORMAT_MILLIS = '%Y-%m-%dT%H:%M:%S.%fZ'

The %f produces time with microseconds, for example: 2020-03-18T19:43:18.115783Z.


However, when interacting the AWS s3 and sns apis, I receive DateTimes like this:

2020-03-02T22:32:13.240Z
i.e. milliseconds. 

This seems like a simple change to the utils. TIMESTAMP_FORMAT_MILLIS is named as if it should be millis as well. This is seems like a simple change. Is there a reason it should be microseconds?
self.subscriber['RawMessageDelivery'] = 'true'
        action = {
            'Message': ['msg'],
            'Subject': ['subject'],
            'MessageAttributes.entry.1.Name': ['attr1'],
            'MessageAttributes.entry.1.Value.DataType': ['String'],
            'MessageAttributes.entry.1.Value.StringValue': ['value1'],
            'MessageAttributes.entry.2.Name': ['attr2'],
            'MessageAttributes.entry.2.Value.DataType': ['Binary'],
            'MessageAttributes.entry.2.Value.BinaryValue': ['value2'.encode('utf-8')],
            'MessageAttributes.entry.3.Name': ['attr3'],
            'MessageAttributes.entry.3.Value.DataType': ['Number'],
            'MessageAttributes.entry.3.Value.StringValue': ['3'],
        }
        attributes = sns_listener.get_message_attributes(action)
        result = sns_listener.create_sqs_message_attributes(self.subscriber, attributes)
        self.assertEqual(result['attr1']['DataType'], 'String')
        self.assertEqual(result['attr1']['StringValue'], 'value1')
        self.assertEqual(result['attr2']['DataType'], 'Binary')
        self.assertEqual(result['attr2']['BinaryValue'], 'value2'.encode('utf-8'))
        self.assertEqual(result['attr3']['DataType'], 'Number')
        self.assertEqual(result['attr3']['StringValue'], '3.0')
    def test_only_one_subscription_per_topic_per_endpoint(self):