fix: 🐛 remove aria-hidden as per PageSpeed Insights' test results

Signed-off-by: WaitSpring <me@waitspring.com>

templates/UserMenu.mustache

@@ -20,7 +20,6 @@
 		class="mw-checkbox-hack-button citizen-header__button" 
 		for="citizen-userMenu__checkbox"
 		title="{{msg-citizen-usermenu-toggle}}"
-		aria-hidden="true"
 		tabindex="0">
 		<span class="citizen-ui-icon mw-ui-icon-wikimedia-userAvatar"></span>
 		<span>{{msg-citizen-usermenu-toggle}}</span>