fix: update typescript declarations

types/connector.d.ts

@@ -15,6 +15,7 @@ export interface Connector {
   disconnect(callback?: Callback): PromiseOrVoid; // Disconnect from the underlying system
   ping(callback?: Callback): PromiseOrVoid; // Ping the underlying system
   execute?(...args: any[]): Promise<any>;
+  [property: string]: any; // Other properties that vary by connectors
 }
 
 /**

types/persisted-model.d.ts

@@ -154,7 +154,7 @@ export declare class PersistedModel extends ModelBase {
     data: PersistedData,
     options?: Options,
     callback?: Callback<PersistedModel>,
-  ): PromiseOrVoid<PersistedModel>;
+  ): PromiseOrVoid<[PersistedModel, boolean]>;
 
   /**
    * Check whether a model instance exists in database.