Workers KV backup

Copy the content of a Workers KV namespace locally.

python3 ./backup.py --api_token=... --cf_account_id=... --kv_namespace_id=...

Flags:

• api_token: Cloudflare's API token (Permission: Workers KV readonly)
• cf_account_id: Cloudflare's Account ID
• kv_namespace_id: Workers KV's namespace ID
• dest: Optional, backup location (default is ./data)