Replace [hxtorch|pynn-brainscales] pkg-config by virtual package

See merge request technical-coordination/project-internal/devops/platform/ebrains-spack-builds!175

Suggested by CINECA.

update py-pynn to 0.10.1

See merge request technical-coordination/project-internal/devops/platform/ebrains-spack-builds!168

Add Brian2

See merge request technical-coordination/project-internal/devops/platform/ebrains-spack-builds!165

Add py-nixio

See merge request technical-coordination/project-internal/devops/platform/ebrains-spack-builds!164

Add pynwb and dependency

See merge request technical-coordination/project-internal/devops/platform/ebrains-spack-builds!162

Add fairgraph and ebrains-kg-core

See merge request technical-coordination/project-internal/devops/platform/ebrains-spack-builds!161

Update Neo package to 0.11.0

See merge request technical-coordination/project-internal/devops/platform/ebrains-spack-builds!160

add-biobb-gromacs

See merge request technical-coordination/project-internal/devops/platform/ebrains-spack-builds!158

Master

See merge request technical-coordination/project-internal/devops/platform/ebrains-spack-builds!157

Fix oppulance caching behavior

See merge request technical-coordination/project-internal/devops/platform/ebrains-spack-builds!151

Previously, we used a custom do_fetch() to download some additional files
needed for the build and to prepare the build folder.
Now, we use spack to track all resources (i.e. download the additional files
itself) and only setup the build folder in install().

Re-try "Update BrainScaleS-2 to latest HEAD"

See merge request technical-coordination/project-internal/devops/platform/ebrains-spack-builds!150

This reverts commit 674e26c0

This reverts commit 017e5e23

This reverts commit 595d9443