feat: v0.5.5 - enhanced priority fee system and dependency updates

- Update solana-streamer-sdk to 0.4.1
- Refactor priority fee API (custom_buy_tip_fee → custom_priority_fee)
- Simplify documentation and clean up examples

BREAKING CHANGE: priority fee parameter type changed

examples/pumpswap_trading/src/main.rs

@@ -188,7 +188,6 @@ async fn pumpswap_trade_with_grpc(mint_pubkey: Pubkey, params: PumpSwapParams) -
             Box::new(params.clone()),
             None,
             true,
-            None,
         )
         .await?;
 
@@ -217,7 +216,6 @@ async fn pumpswap_trade_with_grpc(mint_pubkey: Pubkey, params: PumpSwapParams) -
             Box::new(params.clone()),
             None,
             true,
-            None,
         )
         .await?;