Fix Repository icon, name and label not centered vertically

Readded correct tailwind class for vertical centering

Regression introduced by 65e190ae8b

Fixes #3428.

templates/repo/header.tmpl

@@ -2,7 +2,7 @@
 {{with .Repository}}
 	<div class="ui container">
 		<div class="repo-header">
-			<div class="flex-item gt-ac">
+			<div class="flex-item tw-items-center">
 				<div class="flex-item-leading">
 					{{template "repo/icon" .}}
 				</div>