Patch release v4.50.3

Thanks to the vllm team we have a few more bugs that slipped in!

• [generate] beam search -- fix output cropping (#37080) by @gante

• [blip-2] Fix dtype mismatch when keep in fp32 (#37068) by @zucchini-nlp

• Fix PixtralProcessor patch_size when spatial_merge_size is used (#37019)