Update test-coverage.yaml

Author: hannahlowens

.github/workflows/test-coverage.yaml

@@ -41,3 +41,10 @@ jobs:
           ## --------------------------------------------------------------------
           find ${{ runner.temp }}/package -name 'testthat.Rout*' -exec cat '{}' \; || true
         shell: bash
+
+      - name: Upload test results
+        if: failure()
+        uses: actions/cache/save@v4
+        with:
+          name: coverage-test-failures
+          path: ${{ runner.temp }}/package