chore(deps): update dependency tslint to v6

Author: renovate[bot]

package-lock.json

@@ -76,7 +76,7 @@
     "sort-package-json": "^1.22.1",
     "ts-jest": "^25.0.0",
     "ts-node": "^8.3.0",
-    "tslint": "^5.19.0",
+    "tslint": "^6.0.0",
     "tslint-config-prettier": "^1.18.0",
     "tsutils": "^3.17.1",
     "typedoc": "0.14.0",