chore: set dataChanged flag to false in withBody method

Author: albertcht

src/api-client/src/ApiRequest.php

@@ -182,6 +182,7 @@ public function withoutHeaders(array $headers): static
     public function withBody(string $body): static
     {
         $this->request = $this->request->withBody(new Stream($body));
+        $this->dataChanged = false;
 
         return $this;
     }