Move away from `Repository` to `HfApi` upload files

`Repository` is being deprecated (see https://github.com/huggingface/huggingface_hub/pull/1724) but currently all the evaluate modules are pushed to the hub as spaces with Repository so we’ll need to update that too at some point (from @lvwerra on -private- [slack](https://huggingface.slack.com/archives/C02V5EA0A95/p1697184743250609?thread_ts=1697184108.192679&cid=C02V5EA0A95))

See https://github.com/huggingface/evaluate/blob/main/.github/hub/push_evaluations_to_hub.py