metadata: update to use dovecot cookbook version 2
metadata: update to use dovecot cookbook version 2

onddo/postfix-dovecot-cookbook,onddo/postfix-dovecot-cookbook,zuazo/postfix-dovecot-cookbook,ustuehler/postfix-dovecot-cookbook,onddo/postfix-dovecot-cookbook,zuazo/postfix-dovecot-cookbook,ustuehler/postfix-dovecot-cookbook,RavenB/postfix-dovecot-cookbook,RavenB/postfix-dovecot-cookbook,ustuehler/postfix-dovecot-cookbook,RavenB/postfix-dovecot-cookbook