build(deps): bump gatsby-plugin-manifest from 4.11.1 to 4.13.0 in /docs

Bumps [gatsby-plugin-manifest](https://github.com/gatsbyjs/gatsby/tree/HEAD/packages/gatsby-plugin-manifest) from 4.11.1 to 4.13.0.
- [Release notes](https://github.com/gatsbyjs/gatsby/releases)
- [Changelog](https://github.com/gatsbyjs/gatsby/blob/master/packages/gatsby-plugin-manifest/CHANGELOG.md)
- [Commits](https://github.com/gatsbyjs/gatsby/commits/[email protected]/packages/gatsby-plugin-manifest)

---
updated-dependencies:
- dependency-name: gatsby-plugin-manifest
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

docs/package-lock.json

@@ -16,12 +16,12 @@
     "gatsby-plugin-catch-links": "^4.11.0",
     "gatsby-plugin-emotion": "^7.11.0",
     "gatsby-plugin-google-analytics": "^4.13.0",
-    "gatsby-plugin-manifest": "^4.11.1",
+    "gatsby-plugin-manifest": "^4.13.0",
     "gatsby-plugin-mdx": "^3.11.1",
     "gatsby-plugin-netlify": "^4.3.1",
     "gatsby-plugin-netlify-cache": "^2.0.0",
     "gatsby-plugin-offline": "^5.11.1",
-    "gatsby-plugin-react-helmet": "^5.11.0",
+    "gatsby-plugin-react-helmet": "^5.13.0",
     "gatsby-plugin-react-svg": "^3.1.0",
     "gatsby-plugin-robots-txt": "^1.7.0",
     "gatsby-plugin-sharp": "^4.13.0",