Add a return type declaration to silence a Symfony deprecation notice

Author: mpdude

src/WebfactoryShortcodeBundle.php

@@ -11,7 +11,7 @@
  */
 final class WebfactoryShortcodeBundle extends Bundle
 {
-    public function build(ContainerBuilder $container)
+    public function build(ContainerBuilder $container): void
     {
         parent::build($container);
         $container->addCompilerPass(new ShortcodeCompilerPass());