Bump gatsby-plugin-sharp from 2.6.25 to 2.6.27

Bumps [gatsby-plugin-sharp](https://github.com/gatsbyjs/gatsby/tree/HEAD/packages/gatsby-plugin-sharp) from 2.6.25 to 2.6.27.
- [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@2.6.27/packages/gatsby-plugin-sharp)

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

Author: dependabot-preview[bot]

package-lock.json

@@ -15,7 +15,7 @@
     "gatsby-plugin-manifest": "^2.4.22",
     "gatsby-plugin-offline": "^3.2.22",
     "gatsby-plugin-react-helmet": "^3.3.10",
-    "gatsby-plugin-sharp": "^2.6.25",
+    "gatsby-plugin-sharp": "^2.6.27",
     "gatsby-source-filesystem": "^2.3.24",
     "gatsby-transformer-sharp": "^2.5.12",
     "prop-types": "^15.7.2",