Fix build

[NicolasHug]

All builds started failing with:

/Users/ec2-user/runner/_work/torchcodec/torchcodec/pytorch/torchcodec/src/torchcodec/_core/custom_ops.cpp:87:47: error: must specify at least one argument for '...' parameter of variadic macro [-Werror,-Wgnu-zero-variadic-macro-arguments]
  TORCH_INTERNAL_ASSERT(tensor.is_contiguous());
                                              ^

Probably a BC-breaking change from torch? Anyway, we should probably rely on TORCH_CHECK rather than TORCH_INTERNAL_ASSERT regardless.

[scotts]

Agreed on not using TORCH_INTERNAL_ASSERT - that's leftover from a long while ago.