Add a constant for SERVER_GAME_INFO_EXTENDED max version

Set max version correctly in QueryNetworkGameSocketHandler::SendGameInfo

src/network/core/config.h

@@ -96,4 +96,9 @@ static const uint NETWORK_GRF_NAME_LENGTH           =   80;           ///< Maxim
  */
 static const uint NETWORK_MAX_GRF_COUNT             =   255;
 
+/**
+ * Maximum version supported in PACKET_SERVER_GAME_INFO_EXTENDED
+ */
+static const uint8 SERVER_GAME_INFO_EXTENDED_MAX_VERSION = 1;
+
 #endif /* NETWORK_CORE_CONFIG_H */

src/network/core/game_info.cpp

@@ -434,7 +434,7 @@ void DeserializeNetworkGameInfoExtended(Packet *p, NetworkGameInfo *info)
 	static const Date MAX_DATE = ConvertYMDToDate(MAX_YEAR, 11, 31); // December is month 11
 
 	const uint8 version = p->Recv_uint8();
-	if (version > 1) return; // Unknown version
+	if (version > SERVER_GAME_INFO_EXTENDED_MAX_VERSION) return; // Unknown version
 
 	NewGRFSerializationType newgrf_serialisation = NST_GRFID_MD5;