Upgrade exim-relay (v4.97-r0-0-2 -> v4.97-r0-0-3)

This new version makes the mail spool persistent, so that exim can be
restarted without losing queued messages.

requirements.yml

@@ -19,7 +19,7 @@
   version: v2.0.1-2
   name: etherpad
 - src: git+https://github.com/mother-of-all-self-hosting/ansible-role-exim-relay.git
-  version: v4.97-r0-0-2
+  version: v4.97-r0-0-3
   name: exim_relay
 - src: git+https://gitlab.com/etke.cc/roles/grafana.git
   version: v10.4.1-0