update

.github/workflows/peripheral.yml

@@ -14,6 +14,10 @@ jobs:
     steps:
         - name: Checkout Code
           uses: actions/checkout@v2
+        - name: python3.9
+          uses: actions/setup-python@v2
+          with:
+            python-version: "3.9"
         - name: pip install formatters and checkers
           run: |
               pip3 install mypy isort black pyproject-flake8