add pass step to GitHub Actions (#384)

Same as deepmodeling/deepmd-kit#2141

Author: njzjz

.github/workflows/test.yml

@@ -27,3 +27,8 @@ jobs:
       run: cd tests && coverage run --source=../dpdata -m unittest && cd .. && coverage combine tests/.coverage && coverage report
     - name: Run codecov
       uses: codecov/codecov-action@v3
+  pass:
+    needs: [build]
+    runs-on: ubuntu-latest
+    steps:
+      - run: echo "All jobs passed"