Fix GH actions due to deprecated artifact

Author: mrustl

.github/workflows/R-CMD-check.yaml

@@ -74,7 +74,7 @@ jobs:
 
       - name: Upload check results
         if: failure()
-        uses: actions/upload-artifact@v2
+        uses: actions/upload-artifact@v4
         with:
           name: ${{ runner.os }}-r${{ matrix.config.r }}-results
           path: check