Set the correct application.py path for db-migration task
Set the correct application.py path for db-migration task

Docker app images copy the application files to /app, but the
working directory is not set when SSH-ing into the instance or
running the CF task, so we need to specify the full path.

alphagov/digitalmarketplace-aws,alphagov/digitalmarketplace-aws,alphagov/digitalmarketplace-aws