allow interface

Accept the interface.

I should be able to write something like the following:

```
new codepipeline_actions.EcsDeployAction({
    actionName: 'Deploy-Development',
    input: dockerBuildOutput,
    service: ecs.FargateService.fromFargateServiceArn(this, 'FargateService’, ‘theARN')
})

```

packages/@aws-cdk/aws-codepipeline-actions/lib/ecs/deploy-action.ts

@@ -39,7 +39,7 @@ export interface EcsDeployActionProps extends codepipeline.CommonAwsActionProps
   /**
    * The ECS Service to deploy.
    */
-  readonly service: ecs.BaseService;
+  readonly service: ecs.IService;
 }
 
 /**