wire: correctly parse multi-byte frame types (#3736)

internal/wire/ping_frame.go

@@ -1,21 +1,12 @@
 package wire
 
 import (
-	"bytes"
-
 	"github.com/quic-go/quic-go/internal/protocol"
 )
 
 // A PingFrame is a PING frame
 type PingFrame struct{}
 
-func parsePingFrame(r *bytes.Reader, _ protocol.VersionNumber) (*PingFrame, error) {
-	if _, err := r.ReadByte(); err != nil {
-		return nil, err
-	}
-	return &PingFrame{}, nil
-}
-
 func (f *PingFrame) Append(b []byte, _ protocol.VersionNumber) ([]byte, error) {
 	return append(b, 0x1), nil
 }