[check-r-package]: allow upload-results: never

To never upload the results, not even on failure.

check-r-package/action.yaml

@@ -21,7 +21,9 @@ inputs:
     description: 'Whether to upload all testthat snapshots as an artifact.'
     default: false
   upload-results:
-    description: 'Whether to upload check results for successful runs too.'
+    description: |
+      Whether to upload check results for successful runs too. If 'never',
+      then it does not upload the results, even on failure.
     default: false
   artifact-name:
     description: |
@@ -57,7 +59,7 @@ runs:
       working-directory: ${{ inputs.working-directory }}
 
     - name: Upload check results
-      if: failure() || inputs.upload-results != 'false'
+      if: (failure() && inputs.upload-results != 'never') || inputs.upload-results != 'false'
       uses: actions/upload-artifact@v4
       with:
         name: ${{ inputs.artifact-name || format('{0}-{1}-r{2}-{3}-results', runner.os, runner.arch, matrix.config.r, matrix.config.id || strategy.job-index ) }}