Update report-coverage.yml for new github api

See actions/github-script#242

.github/workflows/report-coverage.yml

@@ -20,7 +20,7 @@ jobs:
         uses: actions/[email protected]
         with:
           script: |
-            var artifacts = await github.actions.listWorkflowRunArtifacts({
+            var artifacts = await github.rest.actions.listWorkflowRunArtifacts({
                owner: context.repo.owner,
                repo: context.repo.repo,
                run_id: ${{github.event.workflow_run.id }},