Fix syntax error in pkgdown workflow

Author: dchodge

.github/workflows/pkgdown.yaml

@@ -23,14 +23,14 @@ jobs:
       # Install dependencies
       - name: Install dependencies
         run: |
-          install.packages('remotes')
-          remotes::install_deps(dependencies = TRUE)
+          Rscript -e "install.packages('remotes')"
+          Rscript -e "remotes::install_deps(dependencies = TRUE)"
 
       # Build the pkgdown site
       - name: Build pkgdown site
         run: |
-          install.packages('pkgdown')
-          pkgdown::build_site()
+          Rscript -e "install.packages('pkgdown')"
+          Rscript -e "pkgdown::build_site()"
 
       # Deploy to gh-pages branch
       - name: Deploy to GitHub Pages