fix: coglet wheel build — pin MINIMUM_PYTHON for ABI3, deduplicate version lists
The manylinux container's default Python changed to 3.8, which doesn't
support ABI3. This caused maturin to produce a cp38-cp38 wheel instead
of cp310-abi3, making the upload glob match nothing and silently
uploading zero files. The downstream download step then fails with
'Artifact not found for name: CogletRustWheel', blocking all
integration tests.
Changes:
- Add MINIMUM_PYTHON env var (3.10) as single source of truth for the
ABI3 floor, used by --interpreter and the verify step
- Add 'Verify ABI3 wheel exists' step to fail fast if the wheel glob
matches nothing
- Replace hardcoded python-version matrix lists in test-python and
test-coglet-python with fromJSON(env.SUPPORTED_PYTHONS)