test: Add missing include

Author: MarcoFalke

src/test/miner_tests.cpp

@@ -1,4 +1,4 @@
-// Copyright (c) 2011-2020 The Bitcoin Core developers
+// Copyright (c) 2011-2021 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
@@ -16,6 +16,7 @@
 #include <util/system.h>
 #include <util/time.h>
 #include <validation.h>
+#include <versionbits.h>
 
 #include <test/util/setup_common.h>