feat: bumb up docker to node 12 (#1622)

Node 10 is active but 12 is the recommended way https://nodejs.org/en/about/releases/ we have been running against v12 for months, so we are safe

Dockerfile

@@ -1,4 +1,4 @@
-FROM node:10.16.3-alpine as builder
+FROM node:12.13.1-alpine as builder
 
 ENV NODE_ENV=production \
     VERDACCIO_BUILD_REGISTRY=https://registry.verdaccio.org
@@ -21,7 +21,7 @@ RUN yarn config set registry $VERDACCIO_BUILD_REGISTRY && \
 
 
 
-FROM node:10.16.3-alpine
+FROM node:12.13.1-alpine
 LABEL maintainer="https://github.com/verdaccio/verdaccio"
 
 ENV VERDACCIO_APPDIR=/opt/verdaccio \