[Security] Workflow book.yml is using vulnerable action peaceiris/actions-gh-pages

[igibek]

The workflow book.yml is referencing action peaceiris/actions-gh-pages using references v2.5.1. However this reference is missing the commit d2178821cb5968f5b7c818210297f3dbeea3114c which may contain fix to the some vulnerability.
The vulnerability fix that is missing by actions version could be related to:
(1) CVE fix
(2) upgrade of vulnerable dependency
(3) fix to secret leak and others.
Please consider to update the reference to the action.