Update dependency eslint-plugin-jsx-a11y to v6

Author: renovate[bot]

package.json

@@ -39,7 +39,7 @@
     "eslint": "^3.19.0",
     "eslint-config-airbnb": "^14.1.0",
     "eslint-plugin-import": "^2.2.0",
-    "eslint-plugin-jsx-a11y": "^4.0.0",
+    "eslint-plugin-jsx-a11y": "^6.0.0",
     "eslint-plugin-react": "^6.10.3",
     "react": "^15.4.1",
     "react-docgen": "^2.12.1",