This PR includes three key improvements:

1. Relaxed Dependency Constraints (Issue Notebook opened in colab cannot run successfully #347): Modified setup.py to use inclusive versioning (>=) for major packages like tensorflow, jax, and dm-reverb. This resolves installation issues in environments like Google Colab where pinned versions conflict with pre-installed packages. Also constrained gym<0.26.0 to ensure API compatibility.
2. EpisodeAdder Documentation (Issue Not enough documentation for EpisodeAdder  #38): Added a detailed docstring to acme.adders.reverb.episode.EpisodeAdder explaining its purpose, arguments, and behavior.
3. Decaying Epsilon Support: Enhanced acme.tf.networks.legal_actions.EpsilonGreedy to accept and use a shared tf.Variable for epsilon. This allows external schedules (e.g., decay) to update the exploration rate dynamically, addressing a previous FIXME.