Please read the release notes at https://github.com/JoinMarket-Org/joinmarket-clientserver/blob/master/docs/release-notes/release-notes-0.9.12.md for details on what this release includes.
This release includes, among other useful things, a bugfix for commitments checking (the mechanism that helps prevent takers DOSing/snooping makers with too many requests); this fix is very important! Read the release notes for more.
Since the project has not been under active development for a considerable time, it is now being archived - the code and releases will remain in place, but there will be no further updates. Do not continue to use the code without having independent confidence that it is not exploitable; something we obviously cannot guarantee. You may want to investigate joinmarket-ng as an alternative codebase for Joinmarket which is under active development, though this is not a recommendation, either.
This release is signed by my (@AdamISZ 's new key, but this is not super-significant; @kristapsk will also add signatures here).