release v7.15.1 (#3384)

* update to release version v7.15.1

* doc: release notes for v7.15.1

Signed-off-by: Jan Larwig <jan@larwig.com>

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Signed-off-by: Jan Larwig <jan@larwig.com>
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Jan Larwig <jan@larwig.com>