[torch_xla] Test 2.6rc3 wheel against 2.6rc3 tag

[tengyifei]

And when we cut the next rc wheel, it will also use the corresponding tag.

Checklist

Before submitting this PR, please make sure (put X in square brackets):

• I have performed a self-review of my code.
• I have necessary comments in my code, particularly in hard-to-understand areas.
• I have run one-shot tests and provided workload links above if applicable.
• I have made or will make corresponding changes to the doc if needed.

[zpcore]

LGTM, thanks!