ci: dockerhub login to increase rate-limit

[denolfe]

Docker Hub has rate-limits for anonymous users. This adds logging in, which will increase the limit.

Example error message

Unable to find image 'mongo:6' locally
  docker: Error response from daemon: toomanyrequests: 
You have reached your pull rate limit. You may increase the limit by authenticating and upgrading: https://www.docker.com/increase-rate-limit.

Example error in pipeline: https://github.com/payloadcms/payload/actions/runs/12911899766/job/36005722765?pr=10723

[github-actions]

🚀 This is included in version v3.19.0