tests: Use explicit imports

test/functional/mining_getblocktemplate_longpoll.py

@@ -4,8 +4,10 @@
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 """Test longpolling with getblocktemplate."""
 
+from decimal import Decimal
+
 from test_framework.test_framework import BitcoinTestFramework
-from test_framework.util import *
+from test_framework.util import get_rpc_proxy, random_transaction
 
 import threading