Fix omitempty bug (#33663) (#33670)

Backport #33663 by @lunny

Fix #33660

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

models/admin/task.go

@@ -44,7 +44,7 @@ func init() {
 // TranslatableMessage represents JSON struct that can be translated with a Locale
 type TranslatableMessage struct {
 	Format string
-	Args   []any `json:"omitempty"`
+	Args   []any `json:",omitempty"`
 }
 
 // LoadRepo loads repository of the task