chore(deps): update dependency lint-staged to v8

Author: renovate-bot

package.json

@@ -15,7 +15,7 @@
     "@types/node": "8.5.2",
     "ava": "0.23.0",
     "husky": "0.14.3",
-    "lint-staged": "6.0.0",
+    "lint-staged": "8.1.2",
     "prettier": "1.9.2",
     "serverless-plugin-typescript": "1.1.5",
     "serverless-apigwy-binary": "0.1.0"