fix(deps): update react monorepo to v18 (major) (#340)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

demo/package-lock.json

@@ -26,8 +26,8 @@
     "gatsby-plugin-sharp": "^4.25.0",
     "gatsby-source-filesystem": "^4.24.0",
     "gatsby-transformer-remark": "^5.24.0",
-    "react": "^17.0.1",
-    "react-dom": "^17.0.1"
+    "react": "^18.0.0",
+    "react-dom": "^18.0.0"
   },
   "devDependencies": {
     "@netlify/functions": "latest",