removeFromGroup: Don't use removed member for credentials

Co-authored-by: Scott Nonnenberg <scott@signal.org>

ts/models/conversations.ts

@@ -2797,7 +2797,7 @@ export class ConversationModel extends window.Backbone
     } else if (this.isMember(serviceId)) {
       await this.modifyGroupV2({
         name: 'removeFromGroup',
-        usingCredentialsFrom: [pendingMember],
+        usingCredentialsFrom: [],
         createGroupChange: () => this.#removeMember(serviceId),
         extraConversationsForSend: [conversationId],
       });