upgraded to guacamole 1.5.3 / postgres 15-bookworm

.env.template

@@ -1,6 +1,5 @@
 HOSTNAME=guacamole.example.com
 GUACADMIN_PASSWORD=ReplaceWithYourSecretPassword
 PORTMAPPING=127.0.0.1:8080:8080
-GUACAMOLE_VER=1.5.0
-MYSQL_VER=8-debian
-POSTGRES_VER=15-bullseye
+GUACAMOLE_VER=1.5.3
+POSTGRES_VER=15-bookworm