Fix pull request branch selector visible without clicking Edit

Caused by go-gitea#22950

Author: brechtvl

templates/repo/issue/view_title.tmpl

@@ -61,7 +61,7 @@
 					{{$.locale.Tr "repo.pulls.title_desc" .NumCommits $headHref $baseHref | Safe}}
 				</span>
 			{{end}}
-			<span id="pull-desc-edit gt-hidden">
+			<span id="pull-desc-edit" class="gt-hidden">
 				<div class="ui floating filter dropdown">
 					<div class="ui basic small button">
 						<span class="text">{{.locale.Tr "repo.pulls.compare_compare"}}: {{$.HeadTarget}}</span>