Re-enable gcc12 toolchain

[atgeller]

cuda 12.6 doesn't work with clang++ 22.1. Re-enable gcc12 toolchain support to work around this.

[mitchdz]

This looks fine to me. Let's get it in to unblock Deployments.

[github-actions]

CI Summary (push) — ❌ failed

Run #25359354444 · ✅ 3 · ⏩ 9 · ❌ 1 · ⛔ 0

❌ Failed or cancelled

Job	Result	Link
devdeps	❌ failure	view

Top-level jobs (13)

Job	Result
binaries	⏩ skipped
build_and_test	⏩ skipped
config_devdeps	⏩ skipped
config_source_build	⏩ skipped
config_wheeldeps	✅ success
devdeps	❌ failure
docker_image	⏩ skipped
gen_code_coverage	⏩ skipped
metadata	✅ success
python_metapackages	⏩ skipped
python_wheels	⏩ skipped
source_build	⏩ skipped
wheeldeps	✅ success

⏩ Skipped jobs (9) — intentionally skipped on PR builds; run on merge_group / workflow_dispatch

Job
binaries
build_and_test
config_devdeps
config_source_build
docker_image
gen_code_coverage
python_metapackages
python_wheels
source_build

All sub-jobs (37) — every matrix leg, with links

Job	Status	Link
Build and test	⏩ skipped	view
CI Summary	❔ in_progress	view
Configure build (devdeps)	⏩ skipped	view
Configure build (source_build)	⏩ skipped	view
Configure build (wheeldeps)	✅ success	view
Create CUDA Quantum installer	⏩ skipped	view
Create Docker images	⏩ skipped	view
Create Python metapackages	⏩ skipped	view
Create Python wheels	⏩ skipped	view
Gen code coverage	⏩ skipped	view
Load dependencies (amd64, gcc12) / Caching	❌ failure	view
Load dependencies (amd64, gcc12) / Finalize	✅ success	view
Load dependencies (amd64, gcc12) / Metadata	✅ success	view
Load dependencies (amd64, llvm) / Caching	❌ failure	view
Load dependencies (amd64, llvm) / Finalize	✅ success	view
Load dependencies (amd64, llvm) / Metadata	✅ success	view
Load dependencies (arm64, gcc12) / Caching	❌ failure	view
Load dependencies (arm64, gcc12) / Finalize	✅ success	view
Load dependencies (arm64, gcc12) / Metadata	✅ success	view
Load dependencies (arm64, llvm) / Caching	✅ success	view
Load dependencies (arm64, llvm) / Finalize	✅ success	view
Load dependencies (arm64, llvm) / Metadata	✅ success	view
Load source build cache	⏩ skipped	view
Load wheel dependencies (amd64, 12.6) / Caching	✅ success	view
Load wheel dependencies (amd64, 12.6) / Finalize	✅ success	view
Load wheel dependencies (amd64, 12.6) / Metadata	✅ success	view
Load wheel dependencies (amd64, 13.0) / Caching	✅ success	view
Load wheel dependencies (amd64, 13.0) / Finalize	✅ success	view
Load wheel dependencies (amd64, 13.0) / Metadata	✅ success	view
Load wheel dependencies (arm64, 12.6) / Caching	✅ success	view
Load wheel dependencies (arm64, 12.6) / Finalize	✅ success	view
Load wheel dependencies (arm64, 12.6) / Metadata	✅ success	view
Load wheel dependencies (arm64, 13.0) / Caching	✅ success	view
Load wheel dependencies (arm64, 13.0) / Finalize	✅ success	view
Load wheel dependencies (arm64, 13.0) / Metadata	✅ success	view
Prepare cache clean-up	❔ queued	view
Retrieve PR info	✅ success	view

⚠️ Required checks (0/4) — 4 missing — declared in .github/required-checks.yml for push

Required check	Status	Link
Build and test (amd64, llvm, openmpi) / Dev environment (Debug)	❔ missing
Build and test (amd64, llvm, openmpi) / Dev environment (Python)	❔ missing
Build and test (arm64, llvm, openmpi) / Dev environment (Debug)	❔ missing
Build and test (arm64, llvm, openmpi) / Dev environment (Python)	❔ missing