fix(starters): update gatsby monorepo (#11999)

This PR contains the following updates:

| Package | Type | Update | Change | References |
|---|---|---|---|---|
| gatsby | dependencies | patch | `^2.1.16` -> `^2.1.17` | [source](https://togithub.com/gatsbyjs/gatsby) |
| gatsby-plugin-manifest | dependencies | patch | `^2.0.18` -> `^2.0.19` | [source](https://togithub.com/gatsbyjs/gatsby) |
| gatsby-plugin-sharp | dependencies | patch | `^2.0.21` -> `^2.0.22` | [source](https://togithub.com/gatsbyjs/gatsby) |

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### Release Notes

<details>
<summary>gatsbyjs/gatsby</summary>

### [`v2.1.17`](https://togithub.com/gatsbyjs/gatsby/compare/gatsby@2.1.16...gatsby@2.1.17)

[Compare Source](https://togithub.com/gatsbyjs/gatsby/compare/gatsby@2.1.16...gatsby@2.1.17)

</details>

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---

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package.json

@@ -13,7 +13,7 @@
     "test": "echo \"Write tests! -> https://gatsby.app/unit-testing\""
   },
   "dependencies": {
-    "gatsby": "^2.1.16",
+    "gatsby": "^2.1.17",
     "react": "^16.8.3",
     "react-dom": "^16.8.3"
   },