build(deps): bump gatsby-plugin-netlify from 2.3.12 to 2.3.13 in /docs

Bumps [gatsby-plugin-netlify](https://github.com/gatsbyjs/gatsby/tree/HEAD/packages/gatsby-plugin-netlify) from 2.3.12 to 2.3.13.
- [Release notes](https://github.com/gatsbyjs/gatsby/releases)
- [Changelog](https://github.com/gatsbyjs/gatsby/blob/master/packages/gatsby-plugin-netlify/CHANGELOG.md)
- [Commits](https://github.com/gatsbyjs/gatsby/commits/gatsby-plugin-netlify@2.3.13/packages/gatsby-plugin-netlify)

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

docs/package-lock.json

@@ -19,7 +19,7 @@
     "gatsby-plugin-google-analytics": "^2.3.13",
     "gatsby-plugin-manifest": "^2.4.23",
     "gatsby-plugin-mdx": "^1.2.30",
-    "gatsby-plugin-netlify": "^2.3.12",
+    "gatsby-plugin-netlify": "^2.3.13",
     "gatsby-plugin-netlify-cache": "^1.2.0",
     "gatsby-plugin-offline": "^3.2.22",
     "gatsby-plugin-react-helmet": "^3.3.10",