title: Formik Input force lowercased
body: <p>I have a react Formik form that I want to stop users from entering Uppercased letters. I have a YUP check to ensure no uppercased are submitted but it would be helpful if uppercased letters were automatically converted to lowercased as the user types. How do I do this?</p>
  <pre><code>&lt;Formik ...&gt;
    &lt;Form ...&gt;
      &lt;input .../&gt;
    &lt;/Form&gt;
  &lt;/Formik&gt;
  </code></pre>