stream must hint interface not concrete class

Author: WyriHaximus

src/AsyncClient.php

@@ -142,7 +142,7 @@ public function user(string $user): PromiseInterface
         });
     }
 
-    public function stream(): AsyncStreamingClient
+    public function stream(): AsyncStreamingClientInterface
     {
         if (!($this->streamingClient instanceof AsyncStreamingClient)) {
             $this->streamingClient = new AsyncStreamingClient($this->client);

src/AsyncClientInterface.php

@@ -17,5 +17,5 @@ public function profile(): PromiseInterface;
 
     public function user(string $user): PromiseInterface;
 
-    public function stream(): AsyncStreamingClient;
+    public function stream(): AsyncStreamingClientInterface;
 }