Bump JamesIves/github-pages-deploy-action from 4.6.4 to 4.6.8 (#555)

Bumps [JamesIves/github-pages-deploy-action](https://github.com/jamesives/github-pages-deploy-action) from 4.6.4 to 4.6.8.
- [Release notes](https://github.com/jamesives/github-pages-deploy-action/releases)
- [Commits](JamesIves/github-pages-deploy-action@v4.6.4...v4.6.8)

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

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/build_docs.yml

@@ -45,7 +45,7 @@ jobs:
 
     - name: Publish to gh-pages if tagged
       if: startsWith(github.ref, 'refs/tags')
-      uses: JamesIves/github-pages-deploy-action@v4.6.4
+      uses: JamesIves/github-pages-deploy-action@v4.6.8
       with:
         branch: gh-pages
         folder: docs/_build/html