0.4.0

New Features

• Add capacitated vehicle routing problem with time windows generator.
  See #104.
• Reduce the number of symbols in the model returned by
  job_shop_scheduling() generator.
• Add Array::integral(), Array::max(), and Array::min()
  overloads for all existing C++ nodes.
• Add C++ is_integer() function.
• Support Python 3.13.
• Model.add_constraints() now returns the symbol for the constraint.
• Fully support scalar (0-dimensional) indices for advanced indexing
  operations, e.g. A[i, :, j, :] where i and j are nodes with
  scalar output. Previously, this would work only if the final output
  of the indexing operation was also scalar.

Upgrade Notes

• Using advanced indexing nodes with indexing arrays that have a
  higher dimension than one (e.g. A[:, i, :, j] where i and j
  are 2d arrays) has been disabled. Previously, it was possible to
  construct models that used this functionality, but the behavior of
  the model during state initialization and propagation may not have
  been correct.

Bug Fixes

• Fix combined indexing. Previously indexing an array symbol by a
  mixture of arrays, integers, and non-empty slices would always
  result in an error.
• Update AdvancedIndexingNode to check the indices of its indexing
  arrays to prevent out-of-bounds access.
• Fix the case of using scalar indices in an advanced indexing
  operation where the indices were not grouped, e.g. A[:, i, :, j],
  which was technically unsupported but no errors were raised. This
  could also lead to segfaults during state initialization or
  propagation.