add version guard protecting ragged gather reduce kernel

[NuojCheng]

Description

This PR adds version guard protecting ragged_gather_reduce kernel for Jax>=0.10.1.

FIXES: b/518833742

Tests

Ran ragged sort testing using JAX==0.10.1 and JAX==0.10.2.dev20260605, both passed.

Checklist

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• I have made or will make corresponding changes to the doc if needed, including adding new documentation pages to the relevant Table of Contents (toctree directive) as explained in our documentation.

[codecov]

Codecov Report

❌ Patch coverage is 50.00000% with 1 line in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/maxtext/kernels/ragged/ragged_gather_reduce.py	50.00%	1 Missing ⚠️

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