update test-coverage action

Author: JBGruber

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

@@ -83,12 +83,12 @@ jobs:
         if: matrix.config.os == 'ubuntu-latest' && matrix.config.r == 'release'
         run: |
           ## --------------------------------------------------------------------
-          find ${{ runner.temp }}/package -name 'testthat.Rout*' -exec cat '{}' \; || true
+          find '${{ runner.temp }}/package' -name 'testthat.Rout*' -exec cat '{}' \; || true
         shell: bash
 
       - name: Upload test results
         if: failure()
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: coverage-test-failures
           path: ${{ runner.temp }}/package