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

# Type of request: This is a ...

[x] bug report
[ ] feature request

# Detailed description
When I call the Lambda PutFunctionEventInvokeConfig API using the aws-java-sdk, the sdk throws an exception claiming it cannot parse the LastModified timestamp in the response:
```
software.amazon.awssdk.core.exception.SdkClientException: Unable to parse date : 2021-05-28T16:02:30.018Z
        at software.amazon.awssdk.core.exception.SdkClientException$BuilderImpl.build(SdkClientException.java:98)
        at software.amazon.awssdk.protocols.core.StringToInstant.lambda$safeParseDate$0(StringToInstant.java:77)
        at software.amazon.awssdk.protocols.core.StringToInstant.convert(StringToInstant.java:54)
        at software.amazon.awssdk.protocols.core.StringToInstant.convert(StringToInstant.java:32)
```

For comparison, the response for a getting a FunctionEventInvokeConfig for a Lambda of a real AWS account using the aws-cli is the following:
```
{
    "LastModified": "2021-05-27T19:26:43.454000-07:00",
    "FunctionArn": "...",
    ...
}
```

## Expected behavior
LambdaAsyncClient in aws-java-sdk should correctly parse the response for a PutFunctionEventInvokeConfig request.

## Actual behavior
LambdaAsyncClient in aws-java-sdk throws an exception when parsing the LastModified field in the response.

# Steps to reproduce

## Command used to start LocalStack
```
docker run -d --rm --name localstack -p 4566:4566 localstack/localstack:latest
```

## Client code (AWS SDK code snippet, or sequence of "awslocal" commands)
```
val putEventInvokeConfigRequest =
  PutFunctionEventInvokeConfigRequest.builder
    .functionName(functionName)
    .maximumEventAgeInSeconds(21600)
    .maximumRetryAttempts(0)
    .build
lambdaClient.putFunctionEventInvokeConfig(putEventInvokeConfigRequest)
```


try:
        stream_arn = aws_stack.kinesis_stream_arn(stream_name)
        sources = get_event_sources(source_arn=stream_arn)
        for source in sources:
            arn = source['FunctionArn']
            for chunk in chunks(records, source['BatchSize']):
                event = {
                    'Records': [
                        {
                            'eventID': 'shardId-000000000000:{0}'.format(rec['sequenceNumber']),
                            'eventSourceARN': stream_arn,
                            'eventSource': 'aws:kinesis',
                            'eventVersion': '1.0',
                            'eventName': 'aws:kinesis:record',
                            'invokeIdentityArn': 'arn:aws:iam::{0}:role/lambda-role'.format(TEST_AWS_ACCOUNT_ID),
                            'awsRegion': aws_stack.get_region(),
                            'kinesis': rec
                        }
                        for rec in chunk
                    ]
                }
                run_lambda(func_arn=arn, event=event, context={}, asynchronous=not config.SYNCHRONOUS_KINESIS_EVENTS)
    except Exception as e:
        LOG.warning('Unable to run Lambda function on Kinesis records: %s %s' % (e, traceback.format_exc()))
def start_lambda_sqs_listener():
    if SQS_LISTENER_THREAD:
        return
    def send_event_to_lambda(queue_arn, queue_url, lambda_arn, messages, region):
        def delete_messages(result, func_arn, event, error=None, dlq_sent=None, **kwargs):