undeclared identifier 'now', zeus migrate

[sgehrman]

In file included from ./contracts/eos/cardgame/cardgame.cpp:2:
⚠️./contracts/eos/cardgame/gameplay.cpp:15:49: error: use of undeclared identifier 'now'; did you mean 'new'?
auto new_seed_value = (seed_iterator->value + now()) % prime;
^