Change Gravity Forms Submit Input to a Button Element

gfsubmit_to_button.php

// change Gravity Forms submit input to a button element
add_filter( 'gform_submit_button', __NAMESPACE__.'\\form_submit_button', 10, 5 );
function form_submit_button ( $button, $form ){
    $button = str_replace( "input", "button", $button );
    $button = str_replace( "/", "", $button );
    $button .= "{$form['button']['text']}</button>";
    return $button;
}