Support for Pillow >= 8.3.0

[gyes00205]

I try to test picture as below shown but get a strange result not like the result of issue 49.

Therefore, I try to find the bug of test_vistas_single_gpu.py. In line 320 of test_vistas_single_gpu.py, all R values is contiguous in the list before G and B values.

_PALETTE = ImagePalette.ImagePalette(
    palette=list(_PALETTE[:, 0]) + list(_PALETTE[:, 1]) + list(_PALETTE[:, 2]),
    mode="RGB",
)

But in Pillow >= 8.3.0, the list must consist of all channels for one color followed by the next color (e.g. RGBRGBRGB). We can see the description in Pillow 8.3.x version
Maybe I can contribute the code to check the Pillow version in test_vistas_single_gpu.py.