Fix pkgdown workflow failure by installing required template package

[Copilot]

The pkgdown GitHub Actions job failed because site generation uses the golemversetemplate pkgdown template, but that package was not installed in CI. This updates the workflow dependency set so pkgdown::build_site_github_pages() can resolve the configured template.

• Root cause

  • _pkgdown.yml sets template.package: golemversetemplate, which is external to the package dependencies installed by the existing workflow.

• Workflow update

  • Extended setup-r-dependencies in .github/workflows/pkgdown.yaml to install the template package from GitHub before building docs.

with:
  extra-packages: any::pkgdown, github::ThinkR-open/golemversetemplate, local::.
  needs: website