chore(deps): update dependency express to v4.20.0 [security]

Author: renovate[bot]

package.json

@@ -46,7 +46,7 @@
     "chai": "3.5.0",
     "eslint": "3.19.0",
     "eslint-plugin-babel": "3.3.0",
-    "express": "4.16.4",
+    "express": "4.20.0",
     "graphql-server-express": "0.6.0",
     "mocha": "3.5.3",
     "rimraf": "2.6.3",