Fix bug while encoding Fourier features in finetune/finetune_region.py

[manugaurdl]

Bug

Data mismatch error in torch/region/fourier_features with input tensor being FP16 and frequency matrix beign BF16

Error trace

File "/home/manugaur/moondream/moondream/finetune/finetune_region.py", line 179, in main
    encode_coordinate(bb[0].unsqueeze(0), model.region),
  File "/home/manugaur/moondream/moondream/torch/region.py", line 43, in encode_coordinate
    return w.coord_encoder(fourier_features(coord, w.coord_features))
  File "/home/manugaur/moondream/moondream/torch/region.py", line 28, in fourier_features
    f = 2 * math.pi * x @ w
  File "/home/manugaur/vlm_obj_det/.venv/lib/python3.10/site-packages/torch/utils/_device.py", line 103, in __torch_function__
    return func(*args, **kwargs)
RuntimeError: expected mat1 and mat2 to have the same dtype, but got: c10::Half != c10::BFloat16```

Patch

encode_coordinate(bb[0].to(model.region.coord_features.dtype).unsqueeze(0), model.region),
encode_coordinate(bb[1].to(model.region.coord_features.dtype).unsqueeze(0), model.region),
encode_size(bb[2:4].to(model.region.coord_features.dtype).unsqueeze(0), model.region).squeeze(0),