Build(deps-dev): bump gatsby-plugin-typescript from 2.1.2 to 2.1.6 (#…

…3944)

Bumps [gatsby-plugin-typescript](https://github.com/gatsbyjs/gatsby/tree/HEAD/packages/gatsby-plugin-typescript) from 2.1.2 to 2.1.6.
- [Release notes](https://github.com/gatsbyjs/gatsby/releases)
- [Changelog](https://github.com/gatsbyjs/gatsby/blob/master/packages/gatsby-plugin-typescript/CHANGELOG.md)
- [Commits](https://github.com/gatsbyjs/gatsby/commits/gatsby-plugin-typescript@2.1.6/packages/gatsby-plugin-typescript)

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

package.json

@@ -202,7 +202,7 @@
     "gatsby-plugin-react-helmet": "^3.1.3",
     "gatsby-plugin-remove-trailing-slashes": "^2.1.2",
     "gatsby-plugin-styled-components": "^3.1.2",
-    "gatsby-plugin-typescript": "^2.1.2",
+    "gatsby-plugin-typescript": "^2.1.6",
     "got": "^9.6.0",
     "humanize-string": "^2.1.0",
     "husky": "^3.0.4",