more consistent addressingMode

src/Types/GroupMetadata.ts

@@ -11,7 +11,7 @@ export type RequestJoinMethod = 'invite_link' | 'linked_group_join' | 'non_admin
 export interface GroupMetadata {
     id: string
     /** group uses 'lid' or 'pn' to send messages */
-    addressingMode: string
+    addressingMode: "pn" | "lid"
     owner: string | undefined
     subject: string
     /** group subject owner */