chore(package): update @types/node to version 12.0.6

Closes #26

Author: greenkeeper[bot]

package.json

@@ -58,7 +58,7 @@
     "@commitlint/cli": "^7.2.1",
     "@commitlint/config-conventional": "^7.1.2",
     "@types/jest": "^24.0.4",
-    "@types/node": "^11.9.3",
+    "@types/node": "^12.0.6",
     "@typescript-eslint/eslint-plugin": "^1.2.0",
     "@typescript-eslint/parser": "^1.2.0",
     "codecov": "^3.1.0",