fix two errors with gym version==0.26.2

[ZouJiu1]

when I use this repo with gym version==0.26.2, I fix these two errors

1、AttributeError: 'dict' object has no attribute 'all'
2、AttributeError: 'EnvSpec' object has no attribute '_kwargs'. Did you mean: 'kwargs'?

Traceback (most recent call last):
  File "c:\Users\10696\Desktop\access\Hands-on-RL\chapter20.py", line 19, in <module>
    from ma_gym.envs.combat.combat import Combat
  File "C:\Users\10696\Desktop\access\ma-gym\ma_gym\__init__.py", line 10, in <module>
    env_specs = [env_spec for env_spec in envs.registry.all() if 'gym.envs' in env_spec.entry_point]
AttributeError: 'dict' object has no attribute 'all'

and

Traceback (most recent call last):
  File "c:\Users\10696\Desktop\access\Hands-on-RL\chapter20.py", line 19, in <module>
    from ma_gym.envs.combat.combat import Combat
  File "C:\Users\10696\Desktop\access\ma-gym\ma_gym\__init__.py", line 15, in <module>
    kwargs={'name': spec.id, **spec._kwargs}
AttributeError: 'EnvSpec' object has no attribute '_kwargs'. Did you mean: 'kwargs'?

[charfole]

Thanks, it helps me a lot!

[zzxcreate]

thanks