[tests] fix flake8 warnings in zapwallettxes.py

test/functional/zapwallettxes.py

@@ -13,8 +13,12 @@
   available, but that the unconfirmed transaction has been zapped.
 """
 from test_framework.test_framework import BitcoinTestFramework
-from test_framework.util import *
-
+from test_framework.util import (assert_equal,
+                                 assert_raises,
+                                 bitcoind_processes,
+                                 connect_nodes_bi,
+                                 JSONRPCException,
+                                 )
 
 class ZapWalletTXesTest (BitcoinTestFramework):