[Unbound] Upgrade to Alpine 3.8, fixes #1882

data/Dockerfiles/unbound/Dockerfile

@@ -1,4 +1,4 @@
-FROM alpine:3.6
+FROM alpine:3.8
 
 LABEL maintainer "Andre Peters <andre.peters@servercow.de>"
 

docker-compose.yml

@@ -2,7 +2,7 @@ version: '2.1'
 services:
 
     unbound-mailcow:
-      image: mailcow/unbound:1.3
+      image: mailcow/unbound:1.4
       build: ./data/Dockerfiles/unbound
       command: /usr/sbin/unbound
       environment: