fix: Generate credentials

Author: Dr0p42

naas_python/domains/storage/adaptors/secondary/NaasStorageAPIAdaptor.py

@@ -107,7 +107,7 @@ def delete_workspace_storage_object(self,
 
     def generate_credentials(self, workspace_id :str, storage_name: str) -> dict:
 
-        _url = f"{self.host}/workspace/{workspace_id}/storage/credentials"
+        _url = f"{self.host}/workspace/{workspace_id}/storage/credentials/"
 
         api_response = self.make_api_request(
             requests.post,