chore(pkg): update default PPA to 12.x

* Follows on from:
  - #35
  - #45
* Close #44

Author: myii

node/pkg.sls

@@ -8,7 +8,7 @@ nodejs.ppa:
       - pkgrepo: nodejs.ppa
   pkgrepo.managed:
     - humanname: NodeSource Node.js Repository
-    - name: deb {{ salt['pillar.get']('node:ppa:repository_url', 'https://deb.nodesource.com/node_6.x') }} {{ grains['oscodename'] }} main
+    - name: deb {{ salt['pillar.get']('node:ppa:repository_url', 'https://deb.nodesource.com/node_12.x') }} {{ grains['oscodename'] }} main
     - dist: {{ grains['oscodename'] }}
     - file: /etc/apt/sources.list.d/nodesource.list
     - keyid: "68576280"