Bump gatsby from 5.13.6 to 5.13.7 in /site in the gatsby group (#145)

Bumps the gatsby group in /site with 1 update: [gatsby](https://github.com/gatsbyjs/gatsby).


Updates `gatsby` from 5.13.6 to 5.13.7
- [Release notes](https://github.com/gatsbyjs/gatsby/releases)
- [Changelog](https://github.com/gatsbyjs/gatsby/blob/master/CHANGELOG.md)
- [Commits](https://github.com/gatsbyjs/gatsby/compare/[email protected]@5.13.7)

---
updated-dependencies:
- dependency-name: gatsby
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: gatsby
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

site/package.json

@@ -9,7 +9,7 @@
   "dependencies": {
     "@mdx-js/react": "^2.3.0",
     "dracula-prism": "^2.1.16",
-    "gatsby": "^5.13.6",
+    "gatsby": "^5.13.7",
     "gatsby-plugin-catch-links": "^5.13.1",
     "gatsby-plugin-image": "^3.12.3",
     "gatsby-plugin-manifest": "^5.13.1",