Add new optionnal argument in HybridRelations::morphTo()

src/Jenssegers/Mongodb/Eloquent/HybridRelations.php

@@ -169,9 +169,10 @@ trait HybridRelations
      * @param  string $name
      * @param  string $type
      * @param  string $id
+     * @param  string $ownerKey
      * @return \Illuminate\Database\Eloquent\Relations\MorphTo
      */
-    public function morphTo($name = null, $type = null, $id = null)
+    public function morphTo($name = null, $type = null, $id = null, $ownerKey = null)
     {
         // If no name is provided, we will use the backtrace to get the function name
         // since that is most likely the name of the polymorphic interface. We can