feat: use gpu to compute the distance matrix

[loiccoyle]

• add Mosaic.d_matrix_cuda to compute the matrix with gpu (requires installing with pip install 'phomo[cuda]')
• update numpy version to 2.0.0
• fix some minor issues in tests

breaking changes:

• Mosaic.compute_d_matrix renamed to Mosaic.d_matrix
• Mosaic.build takes only the distance matrix and no longer computes it:

# before
mosaic.build(metric="greyscale")  
# after
mosaic.build(mosaic.d_matrix(metric="greyscale"))

closes #3