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

Author: renovate-bot

package.json

@@ -29,7 +29,7 @@
     "prettier": "1.16.4",
     "semantic-release": "15.6.0",
     "ts-jest": "23.10.5",
-    "tslint": "5.12.1",
+    "tslint": "5.20.0",
     "tslint-config-prettier": "1.18.0",
     "typescript": "3.3.3"
   },