Fix label selector popup width (issue creation)

This aligns the popup width of the label selector during issue creation
to the width of the label selector in an already created issue.

(The inherited width from "ui form" is reset to prevent width: 100% on the
input element in the search box.)

(cherry picked from commit b32a03531c)

templates/repo/issue/labels/labels_selector_field.tmpl

@@ -9,7 +9,7 @@
 		{{if or .Labels .OrgLabels}}
 			<div class="ui icon search input">
 				<i class="icon">{{svg "octicon-search" 16}}</i>
-				<input type="text" placeholder="{{ctx.Locale.Tr "repo.issues.filter_labels"}}">
+				<input class="tw-w-auto" type="text" placeholder="{{ctx.Locale.Tr "repo.issues.filter_labels"}}">
 			</div>
 		{{end}}
 		<a class="no-select item" href="#">{{ctx.Locale.Tr "repo.issues.new.clear_labels"}}</a>