chore(main): release arize-phoenix 3.8.0 (#2490)

* chore(main): release arize-phoenix 3.8.0

* Add release notes

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Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Dustin Ngo <dustin@arize.com>