security/openbao: Update 2.6.1 => 2.6.2

Changelog:
https://github.com/openbao/openbao/blob/v2.6.2/CHANGELOG.md

PR: 297666
Security: GHSA-rh46-vc3j-w2w3
Security: GHSA-g892-p242-8g86
Sponsored by: UNIS Labs
MFH: 2026Q3

(cherry picked from commit 5bfe8bc273fc86ca1525746a8a28a24dbaf82dc9)