workers.conf: controller listen to localhost instead of 127.0.0.1

the rspamc controller default host is "localhost" and using by default 127.0.0.1 for rspamd controller is an issue on hosts using IPv6 as "localhost".

conf/workers.conf

@@ -9,7 +9,7 @@ worker {
 }
 worker {
     type = "controller";
-    bind_socket = "127.0.0.1:11334";
+    bind_socket = "localhost:11334";
     count = 1;
 }
 worker {