Add sane logging timestamp format

roles/dovecot/templates/conf.d/10-logging.conf.j2

@@ -0,0 +1,8 @@
+# {{ ansible_managed }}
+# Dovecot configuration for Aurore
+# More info at https://gitea.auro.re/Aurore/ansible
+# And on the Dovecot wiki : https://doc.dovecot.org/
+
+# Prefix for each line written to log file. % codes are in strftime(3) format.
+#log_timestamp = "%b %d %H:%M:%S "
+log_timestamp = "%Y-%m-%d %H:%M:%S "