Bug fix

1. Fix action scaling bug in SAC (#591, @ChenDRAG)

Enhancement

1. Add write_flush in two loggers, fix argument passing in WandbLogger (#581, @Trinkle23897)
2. Update Multi-agent RL docs and upgrade pettingzoo (#595, @ycheng517)
3. Add learning rate scheduler to BasePolicy (#598, @alexnikulkov)
4. Add Jupyter notebook tutorials using Google Colaboratory (#599, @ChenDRAG)
5. Unify utils.network: change action_dim to action_shape (#602, @Squeemos)
6. Update Mujoco bemchmark's webpage (#606, @ChenDRAG)
7. Add Atari results (#600, @gogoduan) (#616, @ChenDRAG)
8. Convert RL Unplugged Atari datasets to tianshou ReplayBuffer (#621, @nuance1979)
9. Implement REDQ (#623, @Jimenius)
10. Improve data loading from D4RL and convert RL Unplugged to D4RL format (#624, @nuance1979)
11. Add vecenv wrappers for obs_norm to support running mujoco experiment with envpool (#628, @Trinkle23897)