How to run Text Generation model (GPT2) on Transformers-cli serve?

Hi,
Iā€™m trying to run a text-generation model GPT2 on transformer-cli serve. I used below code
Creating API :
transformers-cli serve --task=text-generation --model=gpt2

Calling API:
curl -X POST http://localhost:8888/forward -H ā€œaccept: application/jsonā€ -H ā€œContent-Type: application/jsonā€ -d ā€˜{ā€œinputsā€:ā€œWhat is Deep Learningā€,ā€œparametersā€:{ā€œmax_new_tokensā€:20}}ā€™

But Iā€™m getting below error in the response. Looks like the API is expecting some specific input format.
{ā€œdetailā€:[{ā€œtypeā€:ā€œjson_invalidā€,ā€œlocā€:[ā€œbodyā€,0],ā€œmsgā€:ā€œJSON decode errorā€,ā€œinputā€:{},ā€œctxā€:{ā€œerrorā€:ā€œExpecting valueā€}}]}

Let me know what is the write format to call the text-generation API