Try Debian 10 buster with Docker

Dockerfile

@@ -1,4 +1,4 @@
-FROM debian:jessie-slim
+FROM debian:buster-slim
 MAINTAINER wekan
 
 # Declare Arguments
@@ -13,7 +13,7 @@ ARG SRC_PATH
 
 # Set the environment variables (defaults where required)
 # paxctl fix for alpine linux: https://github.com/wekan/wekan/issues/1303
-ENV BUILD_DEPS="apt-utils wget curl bzip2 build-essential python git ca-certificates gcc-4.9 paxctl"
+ENV BUILD_DEPS="apt-utils gnupg wget curl bzip2 build-essential python git ca-certificates gcc-7 paxctl"
 ENV GOSU_VERSION=1.10
 ENV NODE_VERSION ${NODE_VERSION:-v8.9.3}
 ENV METEOR_RELEASE ${METEOR_RELEASE:-1.6.0.1}