chore(docker): add dockerhub login step in ci

[jeffladiray]

Pull Request checklist:

• [x] Write an explicit title for the Pull Request, following Conventional Commits specification
• [ ] Create automatic tests
• [ ] No automatic tests failures
• [ ] Test manually the implemented changes
• [ ] Review my own code (indentation, syntax, style, simplicity, readability)
• [ ] Wonder if you can improve the existing code

See: https://docs.travis-ci.com/user/docker/#pushing-a-docker-image-to-a-registry. We will not be pushing docker images from here, but the login step is still valid. According to docker new terms of pull limit (https://www.docker.com/increase-rate-limits#:~:text=Anonymous%20and%20Free%20Docker%20Hub,%3A%20toomanyrequests%3A%20Too%20Many%20Requests.&text=You%20have%20reached%20your%20pull%20rate%20limit) this should be enough to double our pull capacity (200 pulls/6h)

[forest-bot]

:tada: This PR is included in version 3.10.6 :tada:

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot :package::rocket:

[forest-bot]

:tada: This PR is included in version 4.0.0-beta.5 :tada:

The release is available on:

• npm package (@beta dist-tag)
• GitHub release

Your semantic-release bot :package::rocket: