Handle empty fee_rate_bps values in trade responses

Author: Daniel Kislitsya

src/clob/types/response.rs

@@ -388,7 +388,8 @@ pub struct TradeResponse {
     pub asset_id: U256,
     pub side: Side,
     pub size: Decimal,
-    pub fee_rate_bps: Decimal,
+    #[serde(deserialize_with = "empty_string_as_zero")]
+    pub fee_rate_bps: Decimal,,
     pub price: Decimal,
     pub status: TradeStatusType,
     #[serde_as(as = "TimestampSeconds<String>")]
@@ -518,7 +519,8 @@ pub struct MakerOrder {
     pub maker_address: Address,
     pub matched_amount: Decimal,
     pub price: Decimal,
-    pub fee_rate_bps: Decimal,
+    #[serde(deserialize_with = "empty_string_as_zero")]
+    pub fee_rate_bps: Decimal,,
     pub asset_id: U256,
     pub outcome: String,
     pub side: Side,