Increase websocket frame size (from erigon rpc client)

This PR increases frame size, so it'll be possible to use more complicated RPC requests(like `eth_getBlockByNumber`, `trace_` (erigon)), via websocket

from: erigontech/erigon#2739

example block failure: https://etherscan.io/tx/0x1317d973a55cedf9b0f2df6ea48e8077dd176f5444a3423368a46d6e4db89982#internal

rpc/websocket.go

@@ -38,7 +38,7 @@ const (
 	wsPingInterval     = 30 * time.Second
 	wsPingWriteTimeout = 5 * time.Second
 	wsPongTimeout      = 30 * time.Second
-	wsMessageSizeLimit = 15 * 1024 * 1024
+	wsMessageSizeLimit = 32 * 1024 * 1024
 )
 
 var wsBufferPool = new(sync.Pool)