fix(starters): update gatsby monorepo (#12697)

This PR contains the following updates:

| Package | Type | Update | Change | References |
|---|---|---|---|---|
| gatsby | dependencies | patch | [`^2.2.2` -> `^2.2.3`](https://diff.intrinsic.com/gatsby/2.2.2/2.2.3) | [source](https://togithub.com/gatsbyjs/gatsby) |
| gatsby-plugin-sharp | dependencies | patch | [`^2.0.29` -> `^2.0.30`](https://diff.intrinsic.com/gatsby-plugin-sharp/2.0.29/2.0.30) | [source](https://togithub.com/gatsbyjs/gatsby) |

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### Release Notes

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

### [`v2.2.3`](https://togithub.com/gatsbyjs/gatsby/compare/068fb089389fa00873ba534474263a8f831b8e7b...8b8a2e97ef4654de81f59471b7378eb3236731e9)

[Compare Source](https://togithub.com/gatsbyjs/gatsby/compare/gatsby@2.2.2...gatsby@2.2.3)

</details>

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package.json

@@ -13,7 +13,7 @@
     "test": "echo \"Write tests! -> https://gatsby.dev/unit-testing\""
   },
   "dependencies": {
-    "gatsby": "^2.2.2",
+    "gatsby": "^2.2.3",
     "react": "^16.8.4",
     "react-dom": "^16.8.4"
   },