Bump JamesIves/github-pages-deploy-action from 4.6.3 to 4.6.8

Bumps [JamesIves/github-pages-deploy-action](https://github.com/jamesives/github-pages-deploy-action) from 4.6.3 to 4.6.8.
- [Release notes](https://github.com/jamesives/github-pages-deploy-action/releases)
- [Commits](JamesIves/github-pages-deploy-action@v4.6.3...v4.6.8)

---
updated-dependencies:
- dependency-name: JamesIves/github-pages-deploy-action
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/book.yml

@@ -28,7 +28,7 @@ jobs:
           fi
 
       - name: Publish book
-        uses: JamesIves/[email protected].3
+        uses: JamesIves/[email protected].8
         with:
             branch: ${{ steps.target.outputs.branch }} # The branch the action should deploy to.
             folder: book/_build/html # The folder the action should deploy.