[testing, do not merge] add pin package to dep for CI testing

[peterd-NV]

Description

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List any dependencies that are required for this change.

Fixes # (issue)

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (existing functionality will not work without user modification)
• Documentation update

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Checklist

• I have read and understood the contribution guidelines
• I have run the pre-commit checks with ./isaaclab.sh --format
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• I have updated the changelog and the corresponding version in the extension's config/extension.toml file
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[isaaclab-review-bot]

Thanks for the PR! Adding pin (Pinocchio) as a dependency for testing makes sense — the codebase has ~19 files that import pinocchio. A few issues to address:

1. Missing version pin

The existing pin-pink==3.1.0 dependency already requires pin>=2.6.3, so Pinocchio is already pulled in on Linux. Adding "pin" without a version constraint means any future breaking release could silently break things. At minimum, pin it to a compatible range:

"pin>=2.6.3",

or match whatever version the test suite is validated against.

2. Missing platform markers

The pin PyPI package has no Windows wheels (only Linux and macOS). Adding it as an unconditional dependency will break pip install isaaclab on Windows. It should have a platform marker, similar to how pin-pink is gated:

f"pin>=2.6.3 ; platform_system != 'Windows'",

or at minimum:

f"pin>=2.6.3 ; platform_system == 'Linux' and ({SUPPORTED_ARCHS_ARM})",

to match the existing pin-pink scope.

3. Placement in the dependency list

The line is added in the general INSTALL_REQUIRES list, but this is described as being "for testing." If it's only needed for tests, consider whether it belongs in an extras_require test group instead. If it's needed at runtime (not just tests), the PR title/description should be updated to reflect that.

4. PR description is empty

The description is still the default template with no actual content filled in. Please describe:

• What test/scenario was failing without this dependency?
• Why pin-pink's transitive dependency on pin isn't sufficient (is this for scenarios that need Pinocchio without Pink?).

None of the checklist items are checked either.

[isaaclab-review-bot]

Three issues with this line:

1. No version constraint — should at minimum be "pin>=2.6.3" to match what pin-pink already requires.
2. No platform marker — pin has no Windows wheels on PyPI. This will break installation on Windows. Should be gated with at least platform_system != 'Windows'.
3. Possibly redundant on Linux — pin-pink==3.1.0 (line 68) already depends on pin>=2.6.3, so on Linux+supported arches Pinocchio is already installed. Is this intended to cover macOS or non-pin-pink test scenarios?

Suggested fix:

f"pin>=2.6.3 ; platform_system != 'Windows'",