Bump Ruby to .tool-versions 3.2.6

What does this MR do?

Bump Ruby to .tool-versions 3.2.6

This Ruby version is the default Ruby version in Omnibus.

Monolith still uses 3.2.4 but 3.2.5 is also part of their .tool-versions.

Related issues

Checklist

See Definition of done.

For anything in this list which will not be completed, please provide a reason in the MR discussion.

Required

• MR title and description are up to date, accurate, and descriptive.
• MR targeting the appropriate branch.
• Latest Merge Result pipeline is green.
• When ready for review, MR is labeled workflowready for review per the Distribution MR workflow.

For GitLab team members

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Expected (please provide an explanation if not completing)

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• Documentation created/updated.
• Tests added.
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