Update opensmtpd stability tag to 1.26.0

Author: wodbot

.env

@@ -93,7 +93,7 @@ POSTGRES_TAG=17-1.35.6
 ADMINER_TAG=5-4.2.4
 APACHE_TAG=2.4-4.15.3
 MEMCACHED_TAG=1-2.19.1
-OPENSMTPD_TAG=7-1.25.0
+OPENSMTPD_TAG=7-1.26.0
 RSYSLOG_TAG=latest
 SELENIUM_CHROME_TAG=3.141
 WEBGRIND_TAG=1-1.36.7