curl --request GET \
  --url https://api.dfns.io/networks/fees \
  --header 'Authorization: Bearer <token>'

{
  "kind": "Bitcoin",
  "network": "Bitcoin",
  "blockNumber": 123,
  "slow": {
    "feeRate": "<string>",
    "blockHorizon": 123
  },
  "standard": {
    "feeRate": "<string>",
    "blockHorizon": 123
  },
  "fast": {
    "feeRate": "<string>",
    "blockHorizon": 123
  }
}