chore(deps): update dependency tslint to v5.20.0

Author: renovate-bot

package-lock.json

@@ -45,7 +45,7 @@
     "source-map-support": "0.5.13",
     "supertest": "4.0.2",
     "ts-jest": "24.0.2",
-    "tslint": "5.19.0",
+    "tslint": "5.20.0",
     "tslint-config-prettier": "1.18.0",
     "typescript": "3.5.3"
   },