Updated child classes constructors

gym_minigrid/envs/doorkey.py

@@ -44,16 +44,16 @@ class DoorKeyEnv(MiniGridEnv):
         self.mission = "use the key to open the door and then get to the goal"
 
 class DoorKeyEnv5x5(DoorKeyEnv):
-    def __init__(self):
-        super().__init__(size=5)
+    def __init__(self, max_steps=None):
+        super().__init__(size=5, max_steps=max_steps)
 
 class DoorKeyEnv6x6(DoorKeyEnv):
-    def __init__(self):
-        super().__init__(size=6)
+    def __init__(self, max_steps=None):
+        super().__init__(size=6, max_steps=max_steps)
 
 class DoorKeyEnv16x16(DoorKeyEnv):
-    def __init__(self):
-        super().__init__(size=16)
+    def __init__(self, max_steps=None):
+        super().__init__(size=16, max_steps=max_steps)
 
 register(
     id='MiniGrid-DoorKey-5x5-v0',