Getting 'unexpected key' error

[rinchsan]

As you can see reported on https://github.com/aws-actions/amazon-ecs-render-task-definition/issues/38#issuecomment-767746385 and aws-actions/amazon-ecs-deploy-task-definition#164 , we are getting the same 'unexpected key' error.

It will be fixed by updating IGNORED_TASK_DEFINITION_ATTRIBUTES.

[rajpawar02]

Facing a similar issue. Can you merge the fixes to main branch