chore(deps): bump gatsby from 2.29.3 to 2.30.1 in /client

Bumps [gatsby](https://github.com/gatsbyjs/gatsby) from 2.29.3 to 2.30.1.
- [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/gatsby@2.29.3...gatsby@2.30.1)

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

client/package.json

@@ -30,7 +30,7 @@
     "enzyme": "^3.10.0",
     "enzyme-adapter-react-16": "^1.15.5",
     "final-form": "^4.20.1",
-    "gatsby": "^2.29.3",
+    "gatsby": "^2.30.1",
     "gatsby-cli": "^2.16.2",
     "gatsby-plugin-advanced-sitemap": "^1.5.6",
     "gatsby-plugin-create-client-paths": "^2.8.0",