hxtorch will soon depend on jax

See merge request technical-coordination/project-internal/devops/platform/ebrains-spack-builds!258

Fix: py-elephant 0.11.2 restrict quantities < 0.14.0

See merge request technical-coordination/project-internal/devops/platform/ebrains-spack-builds!256

update branch

See merge request technical-coordination/project-internal/devops/platform/ebrains-spack-builds!257

update branch

See merge request technical-coordination/project-internal/devops/platform/ebrains-spack-builds!255

Update BrainScaleS packages and py-torch

See merge request technical-coordination/project-internal/devops/platform/ebrains-spack-builds!244

Until now we used a lot of try/except to keep going when preparing the
environment for the build; it should just work now, so let's fail early.

This should fix problems with finding system-installed headers instead of the
spack-provided ones (e.g. googletest). (In some cases sites might inject
include paths via compiler settings (or other means)).

We allow for newer py-pybind11 versions than upstream; upstream pins a specific
version, but, e.g., arbor needs a newer one. Currently, this should just work
fine :).