Remove scipy<1.15 upper bound

[jdblischak]

For the next release, we can remove the scipy<1.15 upper bound. anndata 0.11.2 added support for scipy 1.15, and I submitted a repodata patch to prevent anndata<0.11.2 from co-installing into a conda env with scipy>= 1.15

xref: single-cell-data/TileDB-SOMA#3526, single-cell-data/TileDB-SOMA#3444, conda-forge/conda-forge-repodata-patches-feedstock#937

[johnkerl]

See also single-cell-data/TileDB-SOMA#3444