postfix: Disable SMTPUTF8

postfix has autodetection for enabling it, but when it is enabled and
the remote doesn't support it, the mail bounces. Disable for now until
we actually have a need for it.
Signed-off-by: Florian Pritz <bluewind@xinu.at>

roles/postfix/templates/main.cf.j2

@@ -3,6 +3,8 @@ compatibility_level = 2
 smtpd_banner = $myhostname ESMTP $mail_name
 biff = no
 
+smtputf8_enable = no
+
 append_dot_mydomain = no
 
 {% if postfix_smtpd_public %}