chore: add asssert that withdrawals are active

Author: knst

test/functional/feature_asset_locks.py

@@ -657,6 +657,7 @@ def test_mn_rr(self, node_wallet, node, pubkey):
     def test_withdrawal_fork(self, node_wallet, node, pubkey):
         self.log.info("Testing asset unlock after 'withdrawal' activation...")
 
+        assert softfork_active(self.nodes[0], 'withdrawals')
         self.log.info("Generating several txes by same quorum....")
 
         asset_unlock_tx = self.create_assetunlock(401, COIN, pubkey)