Add download attribute to release attachments (#28739) (#28740)

Backport #28739 by @JakobDev

Fixes #28736

Co-authored-by: JakobDev <jakobdev@gmx.de>

templates/repo/release/list.tmpl

@@ -94,7 +94,7 @@
 									{{if .Attachments}}
 										{{range .Attachments}}
 											<li>
-												<a target="_blank" rel="nofollow" href="{{.DownloadURL}}">
+												<a target="_blank" rel="nofollow" href="{{.DownloadURL}}" download>
 													<strong>{{svg "octicon-package" 16 "gt-mr-2"}}{{.Name}}</strong>
 												</a>
 												<div>