Update actions/setup-python action to v4

Author: renovate[bot]

.github/workflows/action.yaml

@@ -9,7 +9,7 @@ jobs:
     steps:
       - uses: actions/checkout@v2
       - name: Set up Python
-        uses: actions/setup-python@v2
+        uses: actions/setup-python@v4
         with:
           python-version: 3.6.9
       - name: Install dependencies