chore(deps): update dependency @netlify/plugin-gatsby to v3

Author: renovate-bot

package.json

@@ -43,7 +43,7 @@
   },
   "devDependencies": {
     "@emmanuelgautier/renovate-config": "1.2.2",
-    "@netlify/plugin-gatsby": "2.0.2",
+    "@netlify/plugin-gatsby": "3.0.0",
     "@netlify/plugin-lighthouse": "2.1.3",
     "prettier": "2.5.1"
   },