Adding retention policy

install.sh

 turn_shared_secret: "${TURN_STATIC_SECRET}"
 turn_uris: [ "turn:${DOMAIN}?transport=udp" ]
 suppress_key_server_warning: true
+retention:
+  enabled: true
+  default_policy:
+    min_lifetime: 1s
+    max_lifetime: 1s
 EOF
 
 # Replace Password in homeserver.yaml