Update CI for translations to use galaxy-ci token

[KucharczykL]

1. Generate a token (PAT) for the galaxy-ci user
2. Add that PAT as a repository secret (e.g., GALAXY_CI_TOKEN) (Settings -> Secrets and variables -> Actions)

When setting up the token on the galaxy-ci account, use Fine-grained PAT, then select these permissions:

• Repository Access: Select Only select repositories and pick uyuni-project/uyuni-docs.
• Repository Permissions:
  • Contents: Select Read and write (this allows pushing git commits).
  • Metadata: Select Read-only (automatically added).

[jcayouette]

lgtm if you want to try it out. Makes sense.