title: import error when using Material UI mobile time picker
body: <p>I'm trying to use a material-ui mobile time picker from the new material ui release, but I'm getting a node modules import error I can't figure out.
  I tried to recreating the error in stackblitz and codesandbox, no luck.</p>
  <p>error message:
  ./node_modules/@material-ui/core/Paper/Paper.js
  Attempted import error: 'integerPropType' is not exported from '@material-ui/utils'.</p>
  <p>package.json:</p>
  <pre><code>    &quot;@emotion/react&quot;: &quot;^11.4.0&quot;,
      &quot;@emotion/styled&quot;: &quot;^11.3.0&quot;,
      &quot;@material-ui/core&quot;: &quot;^5.0.0-alpha.34&quot;,
      &quot;@material-ui/lab&quot;: &quot;^5.0.0-alpha.34&quot;,
      &quot;react&quot;: &quot;^17.0.2&quot;,
      &quot;react-dom&quot;: &quot;^17.0.2&quot;,
      &quot;react-scripts&quot;: &quot;^4.0.3&quot;,
  </code></pre>
  <p>component code:</p>
  <pre><code>import React, {useState} from 'react'
  import MobileTimePicker  from '@material-ui/lab/MobileTimePicker';
  import TextField from '@material-ui/core/TextField';
  import AdapterDateFns from '@material-ui/lab/AdapterDateFns';
  import LocalizationProvider from '@material-ui/lab/LocalizationProvider';
  
  export default function Day() {
   return( 
      &lt;div&gt;
          &lt;LocalizationProvider dateAdapter={AdapterDateFns}&gt;
              &lt;MobileTimePicker
              label=&quot;For mobile&quot;
              renderInput={(params) =&gt; &lt;TextField {...params} /&gt;}
              /&gt;
        
          &lt;/LocalizationProvider&gt;
      &lt;/div&gt;)
  }
  </code></pre>
  <p>Not sure if this will be helpful but this is the code sandbox that works, and I don't see any differences between my code locally and this sandbox
  <a href="https://codesandbox.io/s/material-ui-mobile-time-picker-s2l3o?file=/src/App.js:89-141" rel="nofollow noreferrer">code-sandbox</a></p>