Bump gatsby from 5.7.0 to 5.9.1

Bumps [gatsby](https://github.com/gatsbyjs/gatsby) from 5.7.0 to 5.9.1.
- [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]@5.9.1)

---
updated-dependencies:
- dependency-name: gatsby
  dependency-type: direct:production
...

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

package.json

@@ -9,7 +9,7 @@
   "dependencies": {
     "@emotion/core": "^10.0.7",
     "@emotion/styled": "^10.0.7",
-    "gatsby": "^5.7.0",
+    "gatsby": "^5.9.1",
     "gatsby-plugin-emotion": "^4.0.4",
     "gatsby-plugin-google-analytics": "^5.7.0",
     "gatsby-plugin-image": "^3.7.0",