chore(package): update @types/node to version 10.12.5

Closes #99

Author: greenkeeper[bot]

package.json

@@ -50,7 +50,7 @@
     "@types/chai": "^4.1.2",
     "@types/minimist": "^1.2.0",
     "@types/mocha": "^2.2.48",
-    "@types/node": "^9.4.6",
+    "@types/node": "^10.12.5",
     "chai": "^4.1.2",
     "del": "^3.0.0",
     "fs-extra": "^5.0.0",