update setup-python action

Author: rongxin-liu

.github/workflows/main.yml

@@ -21,7 +21,7 @@ jobs:
         - 5432:5432
     steps:
     - uses: actions/checkout@v3
-    - uses: actions/setup-python@v3
+    - uses: actions/setup-python@v4
       with:
         python-version: '3.6'
     - name: Setup databases