ci: match pkgdown with epiprocess

Author: dshemetov

.github/workflows/pkgdown.yaml

@@ -41,7 +41,13 @@ jobs:
       - name: Build site
         env:
           DELPHI_EPIDATA_KEY: ${{ secrets.SECRET_EPIDATR_GHACTIONS_DELPHI_EPIDATA_KEY }}
-        run: pkgdown::build_site_github_pages(new_process = FALSE, install = FALSE)
+        run: |
+          if (startsWith("${{ github.event_name }}", "pull_request")) {
+              mode <- ifelse("${{ github.base_ref }}" == "main", "release", "devel")
+          } else {
+              mode <- ifelse("${{ github.ref_name }}" == "main", "release", "devel")
+          }
+          pkgdown::build_site_github_pages(new_process = FALSE, install = FALSE, override=list(PKGDOWN_DEV_MODE=mode))
         shell: Rscript {0}
 
       - name: Deploy to GitHub pages 🚀