Unknown setting: auth_policy_check_before_auth

Hi,

with Lightmeter 2.0 and setup as described in the manual I get the following error on Ubuntu Bionic

# 2.2.33.2 (d6601f4ec): /etc/dovecot/dovecot.conf
# Pigeonhole version 0.4.21 (92477967)
# OS: Linux 4.15.0-163-generic x86_64 Ubuntu 18.04.6 LTS ext4

Unknown setting: auth_policy_check_before_auth

unix_listener auth-userdb {
  mode = 0600
  user = dovecot
  group = dovecot
  }
unix_listener /var/spool/postfix/private/auth {
   group = postfix
   mode = 0666
   user = postfix
 }

Postfix  3.3.0-1ubuntu0.4

smtpd_sasl_path=/var/spool/postfix/private/auth
smtpd_sasl_type=dovecot