test: Fix bip68 sequence test to reflect updated rpc error message

Empact · Empact · commit e710387ca95f · 2018-02-16T11:06:32.000-08:00
The message changed in #12356
diff --git a/test/functional/feature_bip68_sequence.py b/test/functional/feature_bip68_sequence.py
@@ -14,7 +14,7 @@
 SEQUENCE_LOCKTIME_MASK = 0x0000ffff
 
 # RPC error for non-BIP68 final transactions
-NOT_FINAL_ERROR = "64: non-BIP68-final"
+NOT_FINAL_ERROR = "non-BIP68-final (code 64)"
 
 class BIP68Test(BitcoinTestFramework):
     def set_test_params(self):
