Replace admin_url placeholder

Author: aristath

views/page-widgets/challenge.php

@@ -18,7 +18,6 @@
 	<?php echo \esc_html( $prpl_challenge['name'] ); ?>
 </h2>
 
-
 <div class="prpl-challenge-content">
-	<?php echo \wp_kses_post( $prpl_challenge['content'] ); ?>
+	<?php echo \wp_kses_post( str_replace( '{{admin_url}}', \admin_url(), $prpl_challenge['content'] ) ); ?>
 </div>