feat: 🎸 blocklist "allenai/c4" dataset
see https://github.com/huggingface/datasets-preview-backend/issues/17#issuecomment-918515398
feat: 🎸 blocklist "allenai/c4" dataset: see https://github.com/huggingface/datasets-preview-backend/issues/17#issuecomment-918515398