fix(tests): make kernels_pull path assertions work on Windows

[sridipbasu]

Summary

This PR fixes three Windows-only test failures in tests/unit/test_kernels_pull.py.

Problem

The tests were using POSIX-style paths in the mocked values, while the production code builds paths using os.path.join(). This caused the path assertions to fail on Windows even though the production code was working correctly.

Fix

Normalize the mocked base paths so the expected paths match how the production code builds them on each platform.

This is a test-only change and does not modify any production code.

Testing

• Verified the three previously failing tests now pass on Windows.
• Ran the full unit test suite to make sure no other tests were affected.

[sridipbasu]

@stevemessick
Hey, I went ahead and worked on the Windows test failures as well. I opened a separate PR as you requested!

It's a test-only change that makes the test_kernels_pull.py path assertions OS-agnostic without changing any production code. I'd really appreciate it if you could take a look whenever you have time. Thanks!

[sridipbasu]

Also, just wanted to say thanks for all the reviews and guidance over the past week. I've been working on quite a few fixes recently, so I definitely appreciate you taking the time to point things out and explain them. It's been really helpful, and I've learned a lot from your feedback. Thanks again!

[stevemessick]

/gcbrun

[stevemessick]

Thanks!