Install pkgdown template dependency in CI

[Copilot]

The pkgdown GitHub Actions job was failing during site generation because the configured template package was not available in the runner environment. _pkgdown.yml references golemversetemplate, but the workflow only installed pkgdown and the local package.

• Root cause

  • pkgdown::build_site_github_pages() resolved the site template from _pkgdown.yml and aborted because golemversetemplate was not installed.

• Workflow change

  • Updated .github/workflows/pkgdown.yaml so the docs build installs the template package before running pkgdown.

• Resulting behavior

  • The workflow setup now matches the pkgdown configuration, allowing the site build to load the configured template package instead of failing at build time.

- uses: r-lib/actions/setup-r-dependencies@v2
  with:
    extra-packages: any::pkgdown, github::ThinkR-open/golemversetemplate, local::.
    needs: website