Reliability and modernisation improvements

[fetwar]

I recently used this in a project and made some refinements to it.

Changes:

• more clarifying comments & logging
• removed obsolete or unsupported options
  • version in docker-compose.yml
  • --unattended in config.sh remove
    • this was throwing a warning every time on cleanup
• improved docker usage
  • docker secrets instead of read only bind mount for PAT
  • added a health check to the socket service
  • disabled auto updates of runners
    • previously each runner would update itself every time before running, independently downloading and executing the install

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If you'd prefer I can break these down into separate PRs, just let me know.

Any feedback is greatly appreciated