- Update Spack to version 0.21.2
* Bugfixes
+ Containerize: accommodate nested or pre-existing `spack-env`
paths.
+ Fix `setup-env` script, when going back and forth between
instances.
+ Fix using fully-qualified namespaces from root specs.
+ Fix a bug when a required provider is requested for multiple
virtuals.
+ OCI buildcaches:
* only push in parallel when forking.
* use pickleable errors (#42160)
+ Fix using sticky variants in externals.
+ Fix a rare issue with conditional requirements and
multi-valued variants.
* Package updates
+ `rust`: add v1.75, rework a few variants.
+ `py-transformers`: add v4.35.2.
- Fix path to setup-env.sh in the Apptainer template (bsc#1221471).