chore(polkadot): upgrade to v1.2.0 (#905)

Author: renauter

clients/tfchain-client-go/transfer.go

@@ -19,7 +19,7 @@ func (s *Substrate) Transfer(identity Identity, amount uint64, destination Accou
 	}
 	bal := big.NewInt(int64(amount))
 
-	c, err := types.NewCall(meta, "Balances.transfer", dest, types.NewUCompact(bal))
+	c, err := types.NewCall(meta, "Balances.transfer_keep_alive", dest, types.NewUCompact(bal))
 	if err != nil {
 		panic(err)
 	}