Update dependency eslint-plugin-jsx-a11y to v6

Author: renovate[bot]

package.json

@@ -61,7 +61,7 @@
     "eslint": "6.4.0",
     "eslint-config-airbnb": "13.0.0",
     "eslint-plugin-import": "2.2.0",
-    "eslint-plugin-jsx-a11y": "2.2.3",
+    "eslint-plugin-jsx-a11y": "6.8.0",
     "eslint-plugin-react": "6.8.0",
     "jest": "17.0.3",
     "nock": "9.0.2"