### 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_
"Unit": "Seconds",
                },
                {
                    "MetricName": metric_name,
                    "Dimensions": dimension,
                    "Value": 22,
                    "Timestamp": datetime.utcnow().replace(tzinfo=timezone.utc),
                    "Unit": "Seconds",
                },
            ]
            cloudwatch_client.put_metric_data(Namespace=namespace, MetricData=data)
            
            cloudwatch_client.put_metric_alarm(
                AlarmName=alarm_name,
                AlarmDescription="testing cloudwatch alarms",
                MetricName=metric_name,
                Namespace=namespace,
                ActionsEnabled=True,
                Period=30,
                Threshold=2,
                Dimensions=dimension,
                Unit="Seconds",
                Statistic="Average",
                OKActions=[topic_arn_alarm],
                AlarmActions=[topic_arn_alarm],
                EvaluationPeriods=1,
                ComparisonOperator="GreaterThanThreshold",
                TreatMissingData="notBreaching",
            )
            def check_alarm_triggered(expected_state):