### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

When calling 

`cloudWatchClient.EnableAlarmActions(&cloudwatch.EnableAlarmActionsInput{AlarmNames: alarmNames})`

with golang I receive a SerializationError with bytes in the error message saying: 

`<!DOCTYPE HTM |UBLIC "-//W3C//DTD HTML 3.2 Final//EN">.<title>500 Internal Server Error</title>.<h1>Internal Server Error</h1>.<p>The server encountered an internal error and was unable to complete your request. Either the server is overloaded or there is an error in the application.`

I believe this is a bug, since other cloudwatch operations like "DescribeAlarms" work flawlessly with the same client.

### Expected Behavior

I expected the call to go through without any errors

### How are you starting LocalStack?

With a `docker run` command

### Steps To Reproduce

Start localstack, create alarms and call cloudwatch "EnableAlarmActions"

### Environment

_No response_

### Anything else?

_No response_
namespaces = [
            "ns1-%s" % short_uid(),
            "ns2-%s" % short_uid(),
            "ns3-%s" % short_uid(),
        ]
        num_dimensions = 2
        for ns in namespaces:
            for i in range(3):
                rs = cloudwatch_client.put_metric_data(
                    Namespace=ns,
                    MetricData=[
                        {
                            "MetricName": "someMetric",
                            "Value": 123,
                            "Dimensions": [
                                {
                                    "Name": "foo",
                                    "Value": "bar-%s" % (i % num_dimensions),
                                }
                            ],
                        }
                    ],
                )
                assert 200 == rs["ResponseMetadata"]["HTTPStatusCode"]
        rs = cloudwatch_client.list_metrics()
        metrics = [m for m in rs["Metrics"] if m.get("Namespace") in namespaces]
        assert metrics
        assert len(metrics) == len(namespaces) * num_dimensions
    def test_describe_alarms_converts_date_format_correctly(self, cloudwatch_client):