fix: awaiting res.render in send404 controller

>
> A plugin wanted to use `response:rotuer.page` to 404 a specific page on some condition. res.render returns early in send404 and so must be awaited otherwise multiple responses will be sent

src/controllers/404.js

@@ -49,5 +49,5 @@ exports.send404 = async function (req, res) {
 	}
 
 	await middleware.buildHeaderAsync(req, res);
-	res.render('404', { path: validator.escape(path), title: '[[global:404.title]]' });
+	await res.render('404', { path: validator.escape(path), title: '[[global:404.title]]' });
 };