How to change "Search ..." placeholder text

function astra_search_form( $form ) {
    $form = '<section class="search"><form role="search" method="get" id="search-form" action="' . home_url( '/' ) . '" >
   <label class="screen-reader-text" for="s">' . __('',  'astra') . '</label>
    <input type="search" value="' . get_search_query() . '" name="s" id="s" placeholder="Search website" />
    <input type="submit" id="searchsubmit" value="'. esc_attr__('Go', 'astra') .'" />
    </form></section>';
    return $form;
}

add_filter( 'get_search_form', 'astra_search_form' );