Bump gatsby from 5.12.5 to 5.12.6

Bumps [gatsby](https://github.com/gatsbyjs/gatsby) from 5.12.5 to 5.12.6.
- [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]@5.12.6)

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

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

package.json

@@ -5,7 +5,7 @@
   "author": "Robert Dyjas",
   "dependencies": {
     "@mdx-js/react": "^2.3.0",
-    "gatsby": "^5.12.5",
+    "gatsby": "^5.12.6",
     "gatsby-core-utils": "^4.12.0",
     "gatsby-plugin-feed": "^5.12.0",
     "gatsby-plugin-image": "^3.12.0",