Update OpenApi.php (#4108)

Hello, i just add the return type for method `getPaths`

Co-authored-by: Abdouni Abdelkarim <[email protected]>

Author: soyuka

src/OpenApi/OpenApi.php

@@ -61,7 +61,7 @@ public function getServers(): array
         return $this->servers;
     }
 
-    public function getPaths()
+    public function getPaths(): Paths
     {
         return $this->paths;
     }