Get Product Book

curl --request GET \
  --url https://api.coinbase.com/api/v3/brokerage/product_book

{
  "pricebook": {
    "product_id": "BTC-USD",
    "bids": [
      {
        "price": "<string>",
        "size": "<string>"
      }
    ],
    "asks": [
      {
        "price": "<string>",
        "size": "<string>"
      }
    ],
    "time": "<string>"
  },
  "last": "<string>",
  "mid_market": "<string>",
  "spread_bps": "<string>",
  "spread_absolute": "<string>"
}