Opt in to move Alioth mailing list to "temporary" continuation server

The people preparing the discontinuation of Alioth are setting up a transparent replacement for most types of mailing lists. The idea is to use this for the SANE project mailing list in the short term and look for a long term replacement later.

The mailing list owner should be contacted shortly with a request to opt-in. We should opt-in for:

• sane-devel
• sane-announce
• sane-standard (discontinued, see #6 (comment 68724759))

The sane-commit list will most likely not be acceptable. Use the GitLab notification functionality if you want to be kept in the commit loop.