fix(deps): update dependency eslint-plugin-jsx-a11y to ^6.6.1

Author: renovate[bot]

packages/gatsby/package.json

@@ -73,7 +73,7 @@
     "eslint-config-react-app": "^6.0.0",
     "eslint-plugin-flowtype": "^5.10.0",
     "eslint-plugin-import": "^2.26.0",
-    "eslint-plugin-jsx-a11y": "^6.5.1",
+    "eslint-plugin-jsx-a11y": "^6.6.1",
     "eslint-plugin-react": "^7.30.1",
     "eslint-plugin-react-hooks": "^4.5.0",
     "eslint-webpack-plugin": "^2.7.0",