v1.0.4

Changed

• Drop support for Python 3.7 and 3.8.
• Store saved models on Google Cloud Platform rather than in the Git repo.
• x2 speed improvement to some substrates
• Improved install.sh script and installation documentation.
• Various improvements to examples and their documentation.

Fixed

• Puppets were sharing state in Scenarios. #70
• Various issues with RLlib examples.

Added

• .devcontainer for the project.
• pettingzoo example.
• TF1-compatible version of SavedModelPolicy.