fix crashes

[dtrifiro]

• fix _convert_output usage:

  ERROR 06-20 15:57:54 grpc_server.py:123] Generate failed
  ERROR 06-20 15:57:54 grpc_server.py:123] Traceback (most recent call last):
  ERROR 06-20 15:57:54 grpc_server.py:123]   File "/opt/vllm/lib64/python3.11/site-packages/vllm_tgis_adapter/grpc/grpc_server.py", line 140, in func_with_log
  ERROR 06-20 15:57:54 grpc_server.py:123]     return await func(*args, **kwargs)
  ERROR 06-20 15:57:54 grpc_server.py:123]            ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  ERROR 06-20 15:57:54 grpc_server.py:123]   File "/opt/vllm/lib64/python3.11/site-packages/vllm_tgis_adapter/grpc/grpc_server.py", line 264, in Generate
  ERROR 06-20 15:57:54 grpc_server.py:123]     response = self._convert_output(
  ERROR 06-20 15:57:54 grpc_server.py:123]                ^^^^^^^^^^^^^^^^^^^^^
  ERROR 06-20 15:57:54 grpc_server.py:123] TypeError: TextGenerationService._convert_output() takes 3 positional arguments but 5 were given

• fix mypy errors