Update get-stdin to the latest version 🚀 (#4030)

## The dependency [get-stdin](https://github.com/sindresorhus/get-stdin) was updated from `6.0.0` to `7.0.0`.
This version is **not covered** by your **current version range**.

If you don’t accept this pull request, your project will work just like it did before. However, you might be missing out on a bunch of new features, fixes and/or performance improvements from the dependency update.

---

<details>
<summary>Release Notes for v7.0.0</summary>

<p>Breaking:</p>
<ul>
<li>Require Node.js 8 (<a class="issue-link js-issue-link" data-error-text="Failed to load issue title" data-id="433028675" data-permission-text="Issue title is private" data-url="sindresorhus/get-stdin#27" data-hovercard-type="pull_request" data-hovercard-url="/sindresorhus/get-stdin/pull/27/hovercard" href="https://urls.greenkeeper.io/sindresorhus/get-stdin/pull/27">#27</a>)  <a class="commit-link" data-hovercard-type="commit" data-hovercard-url="https://github.com/sindresorhus/get-stdin/commit/7ddb55c32c59b5ae191cbf242e2e2858e96d3e02/hovercard" href="https://urls.greenkeeper.io/sindresorhus/get-stdin/commit/7ddb55c32c59b5ae191cbf242e2e2858e96d3e02"><tt>7ddb55c</tt></a></li>
</ul>
<p>Enhancements:</p>
<ul>
<li>Add TypeScript definition (<a class="issue-link js-issue-link" data-error-text="Failed to load issue title" data-id="433028675" data-permission-text="Issue title is private" data-url="sindresorhus/get-stdin#27" data-hovercard-type="pull_request" data-hovercard-url="/sindresorhus/get-stdin/pull/27/hovercard" href="https://urls.greenkeeper.io/sindresorhus/get-stdin/pull/27">#27</a>)  <a class="commit-link" data-hovercard-type="commit" data-hovercard-url="https://github.com/sindresorhus/get-stdin/commit/7ddb55c32c59b5ae191cbf242e2e2858e96d3e02/hovercard" href="https://urls.greenkeeper.io/sindresorhus/get-stdin/commit/7ddb55c32c59b5ae191cbf242e2e2858e96d3e02"><tt>7ddb55c</tt></a></li>
</ul>
<p><a class="commit-link" href="https://urls.greenkeeper.io/sindresorhus/get-stdin/compare/v6.0.0...v7.0.0"><tt>v6.0.0...v7.0.0</tt></a></p>
</details>

<details>
<summary>Commits</summary>
<p>The new version differs by 3 commits.</p>
<ul>
<li><a href="https://urls.greenkeeper.io/sindresorhus/get-stdin/commit/e30338537e55c6007ccb65df20fc3bf9b1d621dc"><code>e303385</code></a> <code>7.0.0</code></li>
<li><a href="https://urls.greenkeeper.io/sindresorhus/get-stdin/commit/007c561db331a55fc68cc74a6e85daa2fed2a7ad"><code>007c561</code></a> <code>Meta tweaks</code></li>
<li><a href="https://urls.greenkeeper.io/sindresorhus/get-stdin/commit/7ddb55c32c59b5ae191cbf242e2e2858e96d3e02"><code>7ddb55c</code></a> <code>Require Node.js 8, add TypeScript definition (#27)</code></li>
</ul>
<p>See the <a href="https://urls.greenkeeper.io/sindresorhus/get-stdin/compare/83c5c9f9059f0a66a6c9acef03c19546e2cb175b...e30338537e55c6007ccb65df20fc3bf9b1d621dc">full diff</a></p>
</details>

<details>
  <summary>FAQ and help</summary>

  There is a collection of [frequently asked questions](https://greenkeeper.io/faq.html). If those don’t help, you can always [ask the humans behind Greenkeeper](https://github.com/greenkeeperio/greenkeeper/issues/new).
</details>

---


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package.json

@@ -46,7 +46,7 @@
     "debug": "^4.1.1",
     "execall": "^1.0.0",
     "file-entry-cache": "^5.0.1",
-    "get-stdin": "^6.0.0",
+    "get-stdin": "^7.0.0",
     "global-modules": "^2.0.0",
     "globby": "^9.2.0",
     "globjoin": "^0.1.4",