Bump gatsby-plugin-sharp from 5.4.0 to 5.8.1

Bumps [gatsby-plugin-sharp](https://github.com/gatsbyjs/gatsby/tree/HEAD/packages/gatsby-plugin-sharp) from 5.4.0 to 5.8.1.
- [Release notes](https://github.com/gatsbyjs/gatsby/releases)
- [Changelog](https://github.com/gatsbyjs/gatsby/blob/master/packages/gatsby-plugin-sharp/CHANGELOG.md)
- [Commits](https://github.com/gatsbyjs/gatsby/commits/gatsby-plugin-sharp@5.8.1/packages/gatsby-plugin-sharp)

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

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

package.json

@@ -17,7 +17,7 @@
     "gatsby-plugin-manifest": "^5.4.0",
     "gatsby-plugin-react-svg": "^3.3.0",
     "gatsby-plugin-sass": "^6.4.0",
-    "gatsby-plugin-sharp": "^5.4.0",
+    "gatsby-plugin-sharp": "^5.8.1",
     "gatsby-plugin-sitemap": "^6.4.0",
     "gatsby-remark-copy-linked-files": "^6.4.0",
     "gatsby-remark-images": "^7.4.0",