Add pythonrelease and pythonrelease_info grains

[xhon-pelushi]

What does this PR do?

Adds pythonrelease and pythonrelease_info grains.

What issues does this PR fix or reference?

Fixes #59594

Background

pythonversion is a list rather than a dotted string:

pythonversion:
    - 3
    - 11
    - 0
    - final
    - 0

which breaks the <foo>release / <foo>release_info convention the other version grains follow (osrelease is 7.9.2009 with osrelease_info carrying the tuple; likewise kernelrelease).

The issue suggested adding pythonrelease / pythonrelease_info and deprecating pythonversion at some documented future point. This PR does only the additive half — it deliberately does not touch or deprecate pythonversion, so it carries no backwards-compatibility risk. The deprecation is a separate decision for the maintainers.

Result

pythonversion:      [3, 12, 3, 'final', 0]   # unchanged
pythonrelease:      '3.12.3'
pythonrelease_info: [3, 12, 3, 'final', 0]

pythonrelease uses platform.python_version(), which is defined as major.minor.micro and so matches the shape of osrelease.

Tests written?

Yes — added test_pythonrelease to tests/pytests/unit/grains/test_core.py, asserting the dotted form matches both platform.python_version() and major.minor.micro, that pythonrelease_info matches sys.version_info, and that it stays in sync with the pre-existing pythonversion grain.

Verified locally:

• Both test_pythonversion (pre-existing, confirming the old grain is untouched) and the new test_pythonrelease pass against the real salt.grains.core module.
• Checked the two other tests that reference this grain — tests/pytests/integration/modules/grains/test_module.py and tests/pytests/pkg/integration/test_salt_grains.py — both assert membership (assert grain in ret.data) rather than an exact grain set, so adding grains does not affect them.
• black==24.2.0 (the version pinned in .pre-commit-config.yaml) reports both changed files unchanged.

I was not able to run the full tests/pytests/unit/grains/test_core.py suite locally — the salt-factories conftest setup didn't complete in this environment — so CI is the real check on the rest of that file.

Commits signed with GPG?

No

[twangboy]

We'll run these test once the nightlies master branch tests are green. Otherwise they have no hope of passing. Or you could rebase this on the 3008.x branch.

[xhon-pelushi]

Thanks @twangboy — the master nightlies still aren't green, so I've taken the second option: this is now rebased onto 3008.x and the PR base has been retargeted to 3008.x.

For reference, every Nightly (branch: master) run has failed for the last 10 days, including the most recent one against the current master tip (8c502c0b):

Date (UTC)	master	3008.x
2026-08-20	failure	in progress
2026-08-19	failure	success
2026-08-18	failure	success
2026-08-17	failure	success
2026-08-16	failure	success
2026-08-15	failure	success

The rebase was clean — this is a single, purely additive commit and pythonversion() is identical on both branches, so it applied with no conflicts and the diff is unchanged (3 files, +39/-1). platform and sys were already imported in both salt/grains/core.py and tests/pytests/unit/grains/test_core.py on 3008.x, so no new imports were needed.

Happy to move it back to master if you'd rather wait for the nightlies there.