Release v2.0.4

Bugfix

• Fix DiscreteCQL loss metrics #298
• Fix dump ReplayBuffer #299
• Fix InitialStateValueEstimationEvaluator #301
• Fix rendering interface to match the latest Gym version #302

To the rendering fix, I recommend you reinstall d4rl-atari if you use it.

$ pip install -U git+https://github.com/takuseno/d4rl-atari