After [this](DLR-RM/stable-baselines3@9c338f9) by stable-baselines3…

…, DummyVecEnv.reset() method passes a `seed` argument to its list of envs. Since StockTradingEnv.reset() does not expect any argument it results in an error. This commit fixes AI4Finance-Foundation#1022.

finrl/meta/env_stock_trading/env_stocktrading.py

@@ -355,7 +355,7 @@ def step(self, actions):
 
         return self.state, self.reward, self.terminal, False, {}
 
-    def reset(self):
+    def reset(self, seed=None):
         # initiate state
         self.state = self._initiate_state()