chore(package): update eslint to version 6.3.0

Closes #336

Author: greenkeeper[bot]

package.json

@@ -32,7 +32,7 @@
     "codecov": "^3.1.0",
     "csslint": "^1.0.5",
     "eclint": "^2.8.1",
-    "eslint": "^5.11.0",
+    "eslint": "^6.3.0",
     "eslint-config-standard": "^12.0.0",
     "eslint-plugin-compat": "^2.6.3",
     "eslint-plugin-import": "^2.14.0",