Fixes #1010 and #1022 (#1034)

* 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 #1022.

* DummyVecEnv.render() no longer returns the expected state after [this](DLR-RM/stable-baselines3#1327) pull request got merged in `stable-baselines3`. This commit fixes #1010

finrl/agents/stablebaselines3/models.py

@@ -316,7 +316,7 @@ def DRL_prediction(
             trade_obs, rewards, dones, info = trade_env.step(action)
             if i == (len(trade_data.index.unique()) - 2):
                 # print(env_test.render())
-                last_state = trade_env.render()
+                last_state = trade_env.envs[0].render()
 
         df_last_state = pd.DataFrame({"last_state": last_state})
         df_last_state.to_csv(f"results/last_state_{name}_{i}.csv", index=False)