Specify the version of Python interpreter in format.yml

Author: kmyk

.github/workflows/format.yml

@@ -7,10 +7,12 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2
 
     - name: Set up Python
-      uses: actions/setup-python@v1
+      uses: actions/setup-python@v2
+      with:
+        python-version: '3.8'
 
     - name: Install dependencies
       run: pip3 install .[dev]