Update dependency @types/node to v12.6.8 (#114)

Author: renovate[bot]

package-lock.json

@@ -18,7 +18,7 @@
         "@babel/preset-env": "7.5.4",
         "@babel/preset-typescript": "7.3.3",
         "@types/jest": "24.0.15",
-        "@types/node": "12.6.7",
+        "@types/node": "12.6.8",
         "@typescript-eslint/eslint-plugin": "1.12.0",
         "@typescript-eslint/parser": "1.12.0",
         "babel-jest": "24.8.0",