allow missing env dependencies + update readme

docker/environment_minimal.yaml

@@ -0,0 +1,39 @@
+name: tdmpc2
+channels:
+  - pytorch-nightly
+  - nvidia
+  - conda-forge
+  - defaults
+dependencies:
+  - python=3.9.0
+  - pytorch
+  - torchvision
+  - cudatoolkit=11.7
+  - glew
+  - glib
+  - pip==21
+  - pip:
+    - absl-py
+    - glfw
+    - kornia
+    - termcolor
+    - gym==0.21.0
+    - moviepy
+    - ffmpeg
+    - imageio
+    - imageio-ffmpeg
+    - omegaconf
+    - hydra-core
+    - hydra-submitit-launcher
+    - submitit
+    - pandas
+    - patchelf
+    - protobuf
+    - tqdm
+    - setuptools==65.5.0
+    - "cython<3"
+    - dm-control
+    - pillow
+    - tensordict-nightly
+    - torchrl-nightly
+    - wandb