### Is there an existing issue for this?

- [X] I have searched the existing issues

### Feature description

The use case I have in mind is to run Node 16.x Lambdas - the default container registry is `lambci/lambda` which is effectively abandoned. [Not even Node 14.x has been published](https://github.com/lambci/docker-lambda/pull/330). However, switching the registry over to [`amazon/aws-lambda-nodejs`](https://hub.docker.com/r/amazon/aws-lambda-nodejs) still fails to pull the container, since localstack is looking for the tag `nodejs16.x`. I'd like to be able to specify that if the runtime is `nodejs16.x` it just looks for tag `16`.

### 🧑‍💻 Implementation

_No response_

### Anything else?

_No response_
"""Return the event as a stdin string."""
        
        environment["AWS_LAMBDA_EVENT_BODY"] = event_body
        return event_body.encode()
    def _execute(self, lambda_function: LambdaFunction, inv_context: InvocationContext):
        runtime = lambda_function.runtime
        handler = lambda_function.handler
        environment = inv_context.environment = self._prepare_environment(lambda_function)
        event = inv_context.event
        context = inv_context.context
        
        if config.USE_SSL: