use up-to-date r-lib action; update GHA syntax

Author: zkamvar

.github/workflows/template.yml

@@ -86,12 +86,14 @@ jobs:
         id: check-rmd
         working-directory: lesson
         run: |
-          echo "::set-output name=count::$(shopt -s nullglob; files=($(find . -iname '*.Rmd')); echo ${#files[@]})"
+          echo "count=$(shopt -s nullglob; files=($(find . -iname '*.Rmd')); echo ${#files[@]})" >> $GITHUB_OUTPUT
 
       - name: Set up R
         if: steps.check-rmd.outputs.count != 0
-        uses: r-lib/actions/setup-r@master
+        uses: r-lib/actions/setup-r@v2
         with:
+          use-public-rspm: true
+          install-r: false
           r-version: 'release'
 
       - name: Install needed packages

.github/workflows/website.yml

@@ -44,12 +44,14 @@ jobs:
       - name: Look for R-markdown files
         id: check-rmd
         run: |
-          echo "::set-output name=count::$(shopt -s nullglob; files=($(find . -iname '*.Rmd')); echo ${#files[@]})"
+          echo "count=$(shopt -s nullglob; files=($(find . -iname '*.Rmd')); echo ${#files[@]})" >> $GITHUB_OUTPUT
 
       - name: Set up R
         if: steps.check-rmd.outputs.count != 0
-        uses: r-lib/actions/setup-r@master
+        uses: r-lib/actions/setup-r@v2
         with:
+          use-public-rspm: true
+          install-r: false
           r-version: 'release'
 
       - name: Cache R packages