Build/Test Tools: Add missing `<ul>` tag in `tests/qunit/index.html`.

Props ravipatel, JeffPaul.
Fixes #51473.

git-svn-id: https://develop.svn.wordpress.org/trunk@49107 602fd350-edb4-49c9-b593-d223f7449a82

tests/qunit/index.html

@@ -2273,6 +2273,7 @@
 			<div <# if ( data.id ) { #>id="{{ data.id }}"<# } #> class="notice {{ data.className }}"><p>{{{ data.message }}}</p></div>
 		</script>
 		<div hidden>
+			<ul>
 			<li id="wp-admin-bar-updates">
 				<a class="ab-item" href="wp-admin/update-core.php" title="2 Plugin Updates">
 					<span class="ab-icon"></span>
@@ -2303,6 +2304,7 @@
 				</li>
 				</ul>
 			</li>
+			</ul>
 		</div>
 	</body>
 </html>