add priority-gas-price arg to forge script (foundry-rs#5585)

Author: Sabnock01

cli/src/cmd/forge/script/broadcast.rs

@@ -113,8 +113,12 @@ impl ScriptArgs {
                             TypedTransaction::Eip1559(ref mut inner) => {
                                 let eip1559_fees =
                                     eip1559_fees.expect("Could not get eip1559 fee estimation.");
+                                if let Some(priority_gas_price) = self.priority_gas_price {
+                                    inner.max_priority_fee_per_gas = Some(priority_gas_price);
+                                } else {
+                                    inner.max_priority_fee_per_gas = Some(eip1559_fees.1);
+                                }
                                 inner.max_fee_per_gas = Some(eip1559_fees.0);
-                                inner.max_priority_fee_per_gas = Some(eip1559_fees.1);
                             }
                         }
                     }

cli/src/cmd/forge/script/mod.rs

@@ -116,6 +116,15 @@ pub struct ScriptArgs {
     )]
     pub sig: String,
 
+    /// Max priority fee per gas for EIP1559 transactions.
+    #[clap(
+        long,
+        env = "ETH_PRIORITY_GAS_PRICE",
+        value_parser = parse_ether_value,
+        value_name = "PRICE"
+    )]
+    pub priority_gas_price: Option<U256>,
+
     /// Use legacy transactions instead of EIP1559 ones.
     ///
     /// This is auto-enabled for common networks without EIP1559.