Move IRC eggdrops from Freenode to Libera

Summary:
Libera chat is an IRC network used by Nasqueron since May 2021.

As it seems now to be a stable decision, it's probably time to migrate
the IRC eggdrops still there.

Test Plan: Apply for Dæghrefn and Wearg, see they reach Libera on .jump.

Reviewers: dereckson

Reviewed By: dereckson

Maniphest Tasks: T1721

Differential Revision: https://devcentral.nasqueron.org/D2665