remove usage of boost::bind

boost::bind usage was removed in #13743. However a new usage snuck in as
part of 2bc4c3eaf9 (#15225).

src/qt/walletmodel.cpp

@@ -413,7 +413,7 @@ void WalletModel::subscribeToCoreSignals()
     m_handler_transaction_changed = m_wallet->handleTransactionChanged(std::bind(NotifyTransactionChanged, this, std::placeholders::_1, std::placeholders::_2));
     m_handler_show_progress = m_wallet->handleShowProgress(std::bind(ShowProgress, this, std::placeholders::_1, std::placeholders::_2));
     m_handler_watch_only_changed = m_wallet->handleWatchOnlyChanged(std::bind(NotifyWatchonlyChanged, this, std::placeholders::_1));
-    m_handler_can_get_addrs_changed = m_wallet->handleCanGetAddressesChanged(boost::bind(NotifyCanGetAddressesChanged, this));
+    m_handler_can_get_addrs_changed = m_wallet->handleCanGetAddressesChanged(std::bind(NotifyCanGetAddressesChanged, this));
 }
 
 void WalletModel::unsubscribeFromCoreSignals()