Revert livekit_server to v1.9.12-1

This backs out the LiveKit v1.10.0 role bump while we investigate MatrixRTC call failures reported in #5076.
The symptoms appear consistent with livekit/livekit#4384, and the upstream fix in livekit/livekit#4389 has not reached a release yet.

requirements.yml

@@ -42,7 +42,7 @@
   version: v10741-2
   name: jitsi
 - src: git+https://github.com/mother-of-all-self-hosting/ansible-role-livekit-server.git
-  version: v1.10.0-0
+  version: v1.9.12-1
   name: livekit_server
 - src: git+https://github.com/mother-of-all-self-hosting/ansible-role-ntfy.git
   version: v2.19.2-1