title: React formik partialy update initial values
body: <p>In my react component I have these two initial values</p>
  <pre><code> const [initialValues, setInitialValues] = useState({
      name: 'Tom',
      age: 85,
    });
  </code></pre>
  <p>And I have a text field to change the values for the name field. And I have a button to change the age field.</p>
  <p>If I type name as 'Jerry' and press that button to update the age It will update the age to 75 and reset the name 'Jerry' to 'Tom' again.</p>
  <p><a href="https://codesandbox.io/s/formik-re-render-initialvalues-forked-f7pg5" rel="nofollow noreferrer">This is my code</a></p>
  <p>Type Jerry in the text box and hit the button to see that it changes to the &quot;Tom&quot;</p>
  <p>How do I fix this?</p>
  <p>Anyhelp!
  Thanks in advance! =)</p>