bump mainnet HIVE_BLOCKCHAIN_VERSION to 1.28.7

Release carrying the p2p fork-tolerance fixes (!2064, !2065): stale blocks
from slightly-behind peers no longer trigger punitive mass disconnects
(the amplifier behind the 2026-07-09/10 network disruptions), and
disconnect notifications stay decodable.

Only the mainnet definition is bumped.  The testnet and mirrornet
definitions (see #838 - the version is defined in three places) are
deliberately left untouched: changing the testnet version invalidates the
hardcoded block-hash/PoW patterns in the condenser_api unit tests (#839),
and this release contains no consensus changes that would warrant it.

Author: emfrias

libraries/protocol/include/hive/protocol/config.hpp

@@ -137,7 +137,7 @@ using namespace hive::protocol::testnet_blockchain_configuration;
   #define HIVE_CHAIN_ID                         fc::sha256("4200000000000000000000000000000000000000000000000000000000000000")
 #else
   /// Hive mainnet
-  #define HIVE_BLOCKCHAIN_VERSION               ( version(1, 28, 6) )
+  #define HIVE_BLOCKCHAIN_VERSION               ( version(1, 28, 7) )
   #define OLD_CHAIN_ID                          fc::sha256()
   #define HIVE_CHAIN_ID                         fc::sha256("beeab0de00000000000000000000000000000000000000000000000000000000")
 #endif