Add github action which automatically runs tests against latest ComfyUI

[tazlin]

• This should be a matter of getting the HEAD hash from comfyui and changing the COMFYUI_VERSION in hordelib\consts.py to that value, and then kicking off the CI as usual
• This should be run at some fixed frequency (every 5 days?)
  • We do not currently have a permanent CI runner; perhaps a reminder should be sent upon the action running
  • If the hash has not changed, the workflow not be triggered.
• Workflow runs which fail should trigger a suitable alert, ideally with an indication of the version hash which fails.