go/zodb/zeo: msgpack.{Encode,Decode} -> msgpack.{Marshal,Unmarshal}

Encode/decode was deprecated and removed in recent github.com/shamaton/msgpack.

go/zodb/storage/zeo/proto.go

-// Copyright (C) 2018-2020  Nexedi SA and Contributors.
+// Copyright (C) 2018-2021  Nexedi SA and Contributors.
 //                          Kirill Smelkov <kirr@nexedi.com>
 //
 // This program is free software: you can Use, Study, Modify and Redistribute
@@ -104,7 +104,7 @@ func pktEncodeM(m msg) *pktBuf {
 	// arg
 	// it is interface{} - use shamaton/msgpack since msgp does not handle
 	// arbitrary interfaces well.
-	dataArg, err := msgpack.Encode(m.arg)
+	dataArg, err := msgpack.Marshal(m.arg)
 	if err != nil {
 		panic(err) // all our types are expected to be supported by msgpack
 	}
@@ -240,7 +240,7 @@ func pktDecodeM(pkb *pktBuf) (msg, error) {
 	if len(btail) != 0 {
 		return m, derrf(".%d: payload has extra data after message")
 	}
-	err = msgpack.Decode(b, &m.arg)
+	err = msgpack.Unmarshal(b, &m.arg)
 	if err != nil {
 		return m, derrf(".%d: arg: %s", m.msgid, err)
 	}