Retry fixing doc build error

.github/workflows/chipyard-run-tests.yml

@@ -73,7 +73,9 @@ jobs:
           sudo apt-get install -y python3-pip
           sudo pip3 install -r docs/requirements.txt
           make -C docs html
-          cat /tmp/sphinx-err*.log 2>/dev/null
+      - name: Show error log from sphinx if failed
+        if: ${{ steps.job-start.outputs.run_result != 'success' && failure() }}
+        run: cat /tmp/sphinx-err*.log
       - uses: ./.github/actions/job-end
 
   install-riscv-toolchain: