Allow multiple uvicorn workers
This PR allows to use multiple uvicorn workers per pod, and still have correct metrics. See https://github.com/huggingface/datasets-server/issues/250#issuecomment-1204318173.

cc @McPatate and @XciD 
Allow multiple uvicorn workers: This PR allows to use multiple uvicorn workers per pod, and still have correct metrics. See https://github.com/huggingface/datasets-server/issues/250#issuecomment-1204318173.

cc @McPatate and @XciD 