--load-8bit not compatiable for fastchat-t5-3b-v1.0

@DachengLi1 is already working on this.

Since May 22, 2023.

main branch

`python3 -m fastchat.serve.cli --model-path lmsys/fastchat-t5-3b-v1.0 --max-gpu-memory 7Gib --load-8bit`

```
...FastChat/fastchat/model/compression.py:110 in load_compress_model │
│ │
│ 107 │ │ config = AutoConfig.from_pretrained( │
│ 108 │ │ │ model_path, low_cpu_mem_usage=True, torch_dtype=torch_dtype │
│ 109 │ │ ) │
│ ❱ 110 │ │ model = AutoModelForCausalLM.from_config(config) │
│ 111 │ │ linear_weights = get_compressed_list(model) │
│ 112 │ │
│ 113 │ compressed_state_dict = {}

......

ValueError: Unrecognized configuration class for this kind of AutoModel:
AutoModelForCausalLM.
Model type should be one of BartConfig, BertConfig, BertGenerationConfig, BigBirdConfig,
BigBirdPegasusConfig, BioGptConfig, BlenderbotConfig, BlenderbotSmallConfig, BloomConfig,
CamembertConfig, CodeGenConfig, CpmAntConfig, CTRLConfig, Data2VecTextConfig, ElectraConfig,
ErnieConfig, GitConfig, GPT2Config, GPT2Config, GPTBigCodeConfig, GPTNeoConfig, GPTNeoXConfig,
GPTNeoXJapaneseConfig, GPTJConfig, LlamaConfig, MarianConfig, MBartConfig, MegaConfig,
MegatronBertConfig, MvpConfig, OpenAIGPTConfig, OPTConfig, PegasusConfig, PLBartConfig,
ProphetNetConfig, QDQBertConfig, ReformerConfig, RemBertConfig, RobertaConfig,
RobertaPreLayerNormConfig, RoCBertConfig, RoFormerConfig, Speech2Text2Config, TransfoXLConfig,
TrOCRConfig, XGLMConfig, XLMConfig, XLMProphetNetConfig, XLMRobertaConfig, XLMRobertaXLConfig,
XLNetConfig, XmodConfig.
```

I tried to load the model with `model = AutoModelForSeq2SeqLM.from_pretrained(model_path, low_cpu_mem_usage=True)`, it works ok. And then it crash when I input some text.