Don't raise exception on physics error.

This is now default behavior. Raised exceptions can be proglematic
when training agents in batches or in a distributed manner.

src/dm_robotics/panda/environment.py

@@ -88,6 +88,7 @@ def build_task_environment(self) -> subtask_env.SubTaskEnvironment:
 
     env_builder.set_action_space(full_action_space)
     env = env_builder.build()
+    env._env._raise_exception_on_physics_error = False
 
     return env