Update EditPullRequestOption struct (#601)

Reviewed-on: https://gitea.com/gitea/go-sdk/pulls/601
Reviewed-by: techknowlogick <techknowlogick@gitea.io>
Reviewed-by: John Olheiser <john+gitea@jolheiser.com>

gitea/pull.go

@@ -173,6 +173,8 @@ type EditPullRequestOption struct {
 	Labels              []int64    `json:"labels"`
 	State               *StateType `json:"state"`
 	Deadline            *time.Time `json:"due_date"`
+	RemoveDeadline      *bool      `json:"unset_due_date"`
+	AllowMaintainerEdit *bool      `json:"allow_maintainer_edit"`
 }
 
 // Validate the EditPullRequestOption struct