ui: Change icon on title for merged PR to git-merge (#11064)

Signed-off-by: a1012112796 <1012112796@qq.com>

templates/repo/issue/view_title.tmpl

@@ -17,7 +17,7 @@
 		{{end}}
 	</div>
 	{{if .HasMerged}}
-		<div class="ui purple large label">{{svg "octicon-git-pull-request" 16}} {{.i18n.Tr "repo.pulls.merged"}}</div>
+		<div class="ui purple large label">{{svg "octicon-git-merge" 16}} {{.i18n.Tr "repo.pulls.merged"}}</div>
 	{{else if .Issue.IsClosed}}
 		<div class="ui red large label">{{svg "octicon-issue-closed" 16}} {{.i18n.Tr "repo.issues.closed_title"}}</div>
 	{{else if .Issue.IsPull}}