Fix Box2D in fresh install on Ubuntu (#334)

Author: naeioi

scripts/setup_linux.sh

@@ -219,7 +219,7 @@ conda activate garage
   # See https://github.com/openai/gym/issues/100
   # See https://github.com/pybox2d/pybox2d/issues/82
   pip uninstall -y Box2D Box2D-kengz box2d-py
-  pip install Box2D
+  pip install Box2D box2d-py
 
   # We need a MuJoCo key to import mujoco_py
   cp ${_arg_mjkey} "${HOME}"/.mujoco/mjkey.txt