Upgrade Etherpad (v2.2.7-3 -> v2.2.7-4)

requirements.yml

@@ -16,7 +16,7 @@
   version: 129c8590e106b83e6f4c259649a613c6279e937a
   name: docker_sdk_for_python
 - src: git+https://github.com/mother-of-all-self-hosting/ansible-role-etherpad.git
-  version: v2.2.7-3
+  version: v2.2.7-4
   name: etherpad
 - src: git+https://github.com/mother-of-all-self-hosting/ansible-role-exim-relay.git
   version: v4.98-r0-4-2