Cannot use a base image from ECR in Github Actions

[dancorne]

When setting up a Github Workflow to assume an AWS role for pushing/pulling images, serverless-tools should carry through that authentication for the Docker build. However it returns an error when trying to access an internal base image.

Unfortunately I can't find my example in the logs now but it was clear it couldn't pull the base image due to authentication issues. I think it works locally though, maybe because Docker auth works separately to the AWS login IIRC.