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# 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)
```


mkdir, unzip, is_zip_file, run, run_safe, first_char_to_lower, run_for_max_seconds, parse_request_data,
    timestamp_millis, timestamp, now_utc, safe_requests, FuncThread, isoformat_milliseconds, synchronized)
from localstack.services.awslambda import lambda_executors
from localstack.services.generic_proxy import RegionBackend
from localstack.services.awslambda.lambda_utils import (
    DOTNET_LAMBDA_RUNTIMES, multi_value_dict_for_list, get_handler_file_from_name,
    LAMBDA_DEFAULT_HANDLER, LAMBDA_DEFAULT_RUNTIME, LAMBDA_DEFAULT_STARTING_POSITION)
from localstack.utils.analytics import event_publisher
from localstack.utils.http_utils import parse_chunked_data
from localstack.utils.aws.aws_models import LambdaFunction, CodeSigningConfig
LOG = logging.getLogger(__name__)
LAMBDA_POLICY_NAME_PATTERN = 'lambda_policy_%s'
APP_NAME = 'lambda_api'
PATH_ROOT = '/2015-03-31'
ARCHIVE_FILE_PATTERN = '%s/lambda.handler.*.jar' % config.TMP_FOLDER
LAMBDA_SCRIPT_PATTERN = '%s/lambda_script_*.py' % config.TMP_FOLDER
LAMBDA_ZIP_FILE_NAME = 'original_lambda_archive.zip'
LAMBDA_JAR_FILE_NAME = 'original_lambda_archive.jar'
LAMBDA_DEFAULT_TIMEOUT = 3
INVALID_PARAMETER_VALUE_EXCEPTION = 'InvalidParameterValueException'
VERSION_LATEST = '$LATEST'
FUNCTION_MAX_SIZE = 69905067
BATCH_SIZE_RANGES = {
    'kafka': (100, 10000),
    'kinesis': (100, 10000),
    'dynamodb': (100, 1000),
    'sqs': (10, 10)
}
app = Flask(APP_NAME)
EXEC_MUTEX = threading.RLock(1)