Revert "Added typing to agents"

This reverts commit 80dca9f.

gym/f110_gym/envs/base_classes.py

@@ -26,7 +26,6 @@
 Replacement of the old RaceCar, Simulator classes in C++
 Author: Hongrui Zheng
 """
-from typing import List
 import numpy as np
 from f110_gym.envs.dynamic_models import DynamicModel
 from f110_gym.envs.action import CarAction
@@ -407,7 +406,7 @@ def __init__(
         self.ego_idx = ego_idx
         self.params = params
         self.agent_poses = np.empty((self.num_agents, 3))
-        self.agents: List[RaceCar] = []
+        self.agents = []
         self.collisions = np.zeros((self.num_agents,))
         self.collision_idx = -1 * np.ones((self.num_agents,))
         self.model = model