Update memcached stability tag to 2.18.5

Author: wodbot

.env

@@ -92,7 +92,7 @@ KIBANA_TAG=7-5.19.13
 
 ADMINER_TAG=4-3.31.0
 APACHE_TAG=2.4-4.15.2
-MEMCACHED_TAG=1-2.18.3
+MEMCACHED_TAG=1-2.18.5
 OPENSMTPD_TAG=7-1.23.1
 RSYSLOG_TAG=latest
 WEBGRIND_TAG=1-1.36.0