Remove deprecated -rpcserialversion

src/interfaces/chain.h

@@ -334,9 +334,6 @@ public:
     //! Run function after given number of seconds. Cancel any previous calls with same name.
     virtual void rpcRunLater(const std::string& name, std::function<void()> fn, int64_t seconds) = 0;
 
-    //! Current RPC serialization flags.
-    virtual bool rpcSerializationWithoutWitness() = 0;
-
     //! Get settings value.
     virtual common::SettingsValue getSetting(const std::string& arg) = 0;