correct shape of weights

[ckolbPTB]

I tried to provide weights to calc_toeplitz_kernel running this script:

import torch
import torchkbnufft as tkbn

image = torch.randn(1,1,8,8) + 1j * torch.randn(1,1,8,8)
omega = torch.rand(2,12)
weights = torch.ones(1,12)
toep_ob = tkbn.ToepNufft()
kernel = tkbn.calc_toeplitz_kernel(omega, im_size=[8,8], weights=weights)
image = toep_ob(image, kernel)

but it failed, because the dimensions of weights are not correctly adapted in calc_one_batch_toeplitz_kernel. This pull request should fix this.

[mmuckley]

LGTM. Thanks for the contribution @ckolbPTB!