fix(a11y): remove aria-labels from non-interactive elements (#346)

Remove aria-label from `<h1>` of 404 page and disabled LinkButton.

Resolves #263

src/pages/404.astro

@@ -11,7 +11,7 @@ import LinkButton from "@components/LinkButton.astro";
 
   <main id="main-content">
     <div class="not-found-wrapper">
-      <h1 aria-label="404 Not Found">404</h1>
+      <h1>404</h1>
       <span aria-hidden="true">¯\_(ツ)_/¯</span>
       <p>Page Not Found</p>
       <LinkButton