Automatically ping webarchive when a link is inserted on Mixtures

[Tridimensionnel]

It would lessen the problem of dead links which will ultimately appear

[x-yzt]

Useful resources for this:

• WB endpoint to get a snapshot https://archive.org/developers/tutorial-get-snapshot-wayback.html#steps
• SPN2 docs https://docs.google.com/document/d/1Nsv52MvSjbLb2PCpHlat0gkzw0EvtSgpKHu4mk0MnrA/edit
• fly.toml example with Celery worker https://community.fly.io/t/preview-multi-process-apps-get-your-workers-here/2316/13