chore: change issue mail title. (#7064)

* chore: change issue mail title.

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>

* change to fullname method

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>

models/issue_mail.go

@@ -16,7 +16,7 @@ import (
 )
 
 func (issue *Issue) mailSubject() string {
-	return fmt.Sprintf("[%s] %s (#%d)", issue.Repo.Name, issue.Title, issue.Index)
+	return fmt.Sprintf("[%s] %s (#%d)", issue.Repo.FullName(), issue.Title, issue.Index)
 }
 
 // mailIssueCommentToParticipants can be used for both new issue creation and comment.