[#3662] Use Docker Hub credentials for authenticated pulls
[#3662] Use Docker Hub credentials for authenticated pulls

* https://docs.semaphoreci.com/ci-cd-environment/docker-authentication/
* https://docs.semaphoreci.com/ci-cd-environment/docker-authentication/#how-to-authenticate-docker-pulls

akvo/akvo-flow,akvo/akvo-flow,akvo/akvo-flow,akvo/akvo-flow,akvo/akvo-flow