chore(package): update lint-staged to version 7.0.0 (#30)

Author: greenkeeper[bot]

package.json

@@ -46,7 +46,7 @@
     "babel-preset-power-assert": "^2.0.0",
     "babel-register": "^6.26.0",
     "husky": "^0.14.3",
-    "lint-staged": "^5.0.0",
+    "lint-staged": "^7.0.0",
     "mocha": "^5.0.0",
     "power-assert": "^1.4.4",
     "prettier": "^1.7.0",