Add optional onsubscribe callback on TypeScript (#362)

* Add optional `onlisten` callback on TypeScript

* Update types/index.d.ts

Co-authored-by: Minigugus <43109623+Minigugus@users.noreply.github.com>

* Update index.d.ts

Co-authored-by: Minigugus <43109623+Minigugus@users.noreply.github.com>

Author: rafaelcr

types/index.d.ts

@@ -617,7 +617,7 @@ declare namespace postgres {
     listen(channel: string, onnotify: (value: string) => void, onlisten?: () => void): ListenRequest;
     notify(channel: string, payload: string): PendingRequest;
 
-    subscribe(event: string, cb: (row: Row | null, info: ReplicationEvent) => void): Promise<SubscriptionHandle>;
+    subscribe(event: string, cb: (row: Row | null, info: ReplicationEvent) => void, onsubscribe?: () => void): Promise<SubscriptionHandle>;
 
     largeObject(oid?: number, /** @default 0x00020000 | 0x00040000 */ mode?: number): Promise<LargeObject>;