Update cross-env to the latest version � (#759)

Summary:
## The dependency [cross-env](https://github.com/kentcdodds/cross-env) was updated from `6.0.3` 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.

 ---

**Publisher:** [kentcdodds](https://www.npmjs.com/~kentcdodds)
**License:** MIT

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

<h1><a href="https://urls.greenkeeper.io/kentcdodds/cross-env/compare/v6.0.3...v7.0.0">7.0.0</a> (2020-01-25)</h1>
<h3>Features</h3>
<ul>
<li>update dependencies (<a href="https://urls.greenkeeper.io/kentcdodds/cross-env/issues/223" data-hovercard-type="pull_request" data-hovercard-url="/kentcdodds/cross-env/pull/223/hovercard">https://github.com/facebook/flipper/issues/223</a>) (<a href="4ec6f4009d">4ec6f40</a>)</li>
</ul>
<h3>BREAKING CHANGES</h3>
<ul>
<li>Drop Node 8 support</li>
</ul>
</details>

<details>
<summary>Commits</summary>
<p>The new version differs by 1 commits.</p>
<ul>
<li><a href="4ec6f4009d"><code>4ec6f40</code></a> <code>feat: update dependencies (https://github.com/facebook/flipper/issues/223)</code></li>
</ul>
<p>See the <a href="67f21c3254...4ec6f4009d">full diff</a></p>
</details>

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<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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Your [Greenkeeper](https://greenkeeper.io) bot 🌴
Pull Request resolved: https://github.com/facebook/flipper/pull/759

Reviewed By: mweststrate

Differential Revision: D19578528

Pulled By: passy

fbshipit-source-id: 0b3add4ae98fe7ff7d1ed9762a4c546c91b2b282

package.json

@@ -131,7 +131,7 @@
     "async-mutex": "^0.1.3",
     "chalk": "^3.0.0",
     "codemirror": "^5.25.0",
-    "cross-env": "^6.0.3",
+    "cross-env": "^7.0.0",
     "dashify": "^2.0.0",
     "deep-equal": "^2.0.1",
     "detect-port": "^1.1.1",

yarn.lock

@@ -2886,12 +2886,12 @@ create-error-class@^3.0.0:
   dependencies:
     capture-stack-trace "^1.0.0"
 
-cross-env@^6.0.3:
-  version "6.0.3"
-  resolved "https://registry.yarnpkg.com/cross-env/-/cross-env-6.0.3.tgz#4256b71e49b3a40637a0ce70768a6ef5c72ae941"
-  integrity sha512-+KqxF6LCvfhWvADcDPqo64yVIB31gv/jQulX2NGzKS/g3GEVz6/pt4wjHFtFWsHMddebWD/sDthJemzM4MaAag==
+cross-env@^7.0.0:
+  version "7.0.0"
+  resolved "https://registry.yarnpkg.com/cross-env/-/cross-env-7.0.0.tgz#5a3b2ddce51ec713ea58f2fb79ce22e65b4f5479"
+  integrity sha512-rV6M9ldNgmwP7bx5u6rZsTbYidzwvrwIYZnT08hSGLcQCcggofgFW+sNe7IhA1SRauPS0QuLbbX+wdNtpqE5CQ==
   dependencies:
-    cross-spawn "^7.0.0"
+    cross-spawn "^7.0.1"
 
 cross-fetch@^3.0.4:
   version "3.0.4"
@@ -2921,7 +2921,7 @@ cross-spawn@^6.0.0, cross-spawn@^6.0.5:
     shebang-command "^1.2.0"
     which "^1.2.9"
 
-cross-spawn@^7.0.0:
+cross-spawn@^7.0.1:
   version "7.0.1"
   resolved "https://registry.yarnpkg.com/cross-spawn/-/cross-spawn-7.0.1.tgz#0ab56286e0f7c24e153d04cc2aa027e43a9a5d14"
   integrity sha512-u7v4o84SwFpD32Z8IIcPZ6z1/ie24O6RU3RbtL5Y316l3KuHVPx9ItBgWQ6VlfAFnRnTtMUrsQ9MUUTuEZjogg==