Using a ECR image as a base for a docker buiild

[jdamata]

Hello,

Thanks for your work on this drone extension. This works well for me when using a ECR image for a step in drone. Im running into problems when building a docker image in drone that uses a base image from ECR.

Step 1/13 : FROM *.dkr.ecr.ca-central-1.amazonaws.com/

--10 | time="2021-06-10T17:11:46Z" level=fatal msg="Head https://.dkr.ecr.ca-central-1.amazonaws.com/v2/: no basic auth credentials"

Is it possible to inject the docker creds into the drone step so that docker builds can leverage this extension?