Update opensmtpd stability tag to 1.29.3

Author: wodbot

.env

@@ -101,7 +101,7 @@ OPENSEARCH_ADMIN_PASSWORD=VERY%@bad123password
 ADMINER_TAG=5-5.0.4
 APACHE_TAG=2.4-4.18.0
 MEMCACHED_TAG=1-2.23.1
-OPENSMTPD_TAG=7-1.29.2
+OPENSMTPD_TAG=7-1.29.3
 RSYSLOG_TAG=latest
 WEBGRIND_TAG=1-1.49.1
 XHPROF_TAG=3.27.1