chore(package): update @types/node to version 12.6.0

Closes #38

Author: greenkeeper[bot]

package.json

@@ -48,7 +48,7 @@
   "devDependencies": {
     "@types/bunyan": "^1.8.5",
     "@types/core-js": "^2.5.0",
-    "@types/node": "^11.10.0",
+    "@types/node": "^12.6.0",
     "@types/shelljs": "^0.8.3",
     "ava": "^1.2.1",
     "core-js": "^2.6.5",