main/atheme-iris: Fix overlooked consistency issue as in a60b9f07.

There is a further patch in the queue fixing primary group issue.

main/atheme-iris/atheme-iris.pre-install

 #!/bin/sh
 
-adduser -S -D -H -h /usr/share/webapps/atheme-iris -s /sbin/nologin -g iris iris >/dev/null
+adduser -S -D -H -h /usr/share/webapps/atheme-iris -s /sbin/nologin -g iris iris 2>/dev/null
 
 exit 0