fix: resetting buffer for atari correctly

[Anton-Gasse]

While I was playing around with the Atari environment I found this little issue when resetting the buffer.

I think the intended behavior is to replace everything in the buffer with the first observation.

However, when the pooling parameter (buffer size) was > 1 then the first element is iteratively overwritten with the other Elements in the buffer (which are initially arrays with only zeros) and therefore the first observation is always a black image.

The error seems to be putting the self.buffers[0] and dst parameters for the np.copyto() method in the wrong order.
According to the numpy documentation the first parameter should be the destination and the second one the source: https://numpy.org/doc/stable/reference/generated/numpy.copyto.html

The implemented switch in this commit should fix this.
I tested it by adding this little testing script to the main.py file and observed that now the first observation is actually an image from the environment and not a black image:

elif config.script == 'test':

      import matplotlib.pyplot as plt
      env = make_env(config, 0)

      action = {"action": np.int32(0),
                "reset": False,
      }
      for _ in range(4):
        obs = env.step(action)
        plt.imshow(obs["image"], cmap="gray")
        plt.show()

I have not tested yet if that change influences any model behavior in the environment.

Hope to hear from you about, if that is helpful.

Cheers,
Anton