Adjust how client credentials are sent to token service (#483)

sentinelhub/download/session.py

@@ -146,6 +146,7 @@ def _fetch_token(self, request: DownloadRequest) -> JsonDict:
                 client_id=self.config.sh_client_id,
                 client_secret=self.config.sh_client_secret,
                 headers={**self.DEFAULT_HEADERS, **SHConstants.HEADERS},
+                include_client_id=True,
             )
 
     @staticmethod