Update critical GitHub action

Author: PabRod

.github/workflows/r.yml

@@ -16,7 +16,7 @@ jobs:
 
       - uses: r-lib/actions/setup-pandoc@v1
 
-      - uses: actions/cache@v2
+      - uses: actions/cache@v4
         with:
           path: ~/.local/share/renv
           key: ${{ runner.os }}-renv-${{ hashFiles('**/renv.lock') }}