Fix FrameStack

Without the copy, all frames in the stack are the same,
making the FrameStack useless.

src/robofish/gym_guppy/wrappers/observation_wrapper.py

@@ -378,13 +378,12 @@ class FrameStack(gym.ObservationWrapper):
 
     def reset(self, **kwargs):
         obs = self.env.reset(**kwargs)
-        # obs = super(FrameStack, self).reset()
         for _ in range(self.k):
-            self.frames.append(obs)
+            self.frames.append(obs.copy())
         return self._get_obs()
 
     def observation(self, observation):
-        self.frames.append(observation)
+        self.frames.append(observation.copy())
         return self._get_obs()
 
     def _get_obs(self):