Update dependency tslint to v6 (#364)

Co-authored-by: Renovate Bot <bot@renovateapp.com>

Author: renovate[bot]

package-lock.json

@@ -13,7 +13,7 @@
         "chalk": "3.0.0",
         "commander": "5.0.0",
         "strip-json-comments": "3.0.1",
-        "tslint": "5.20.1",
+        "tslint": "6.1.0",
         "typescript": "3.8.3"
     },
     "devDependencies": {