Weight Strategy fix.

[dchatel]

As I mentioned on discord, lines from 1716 to 1732 in ipadapterplus.py can be replaced by this:

image_1 = image[:-1].repeat_interleave(frames, 0)
image_2 = image[1:].repeat_interleave(frames, 0)
weights = weights * (len(image) - 1)
weights_invert = weights[::-1]

In the current implementation, if you have images A,B,C and 4 frames per image, you'll get AAAACCCC and BBBBBBBB with weights 1 to 0 to 1 and 0 to 1 to 0.
With this change, you get AAAABBBB and BBBBCCCC with weights 1 to 0 repeating and 0 to 1 repeating.