feat: Add support for w-auto.

[xiCO2k]

This PR add the w-auto class, that just resets the width of the element, it is useful when you use the Media Queries.

Example:

render(<<<'HTML'
    <div class="my-1 mx-2 w-25 sm:w-auto truncate px-1 bg-red text-black">
        When its a sm screen it will have the width set, but with larger sizes it will have no limitation
    </div>
HTML);

Output

[nunomaduro]

Once tests are fixed, you can merge.