use v2 actions

.github/workflows/main.yml

@@ -10,9 +10,9 @@ jobs:
         # Tested versions based on dates in https://devguide.python.org/versions/#versions
         python-version: ['3.8', '3.9', '3.10', '3.11']
     steps:
-      - uses: actions/checkout@master
+      - uses: actions/checkout@v2
       - name: Setup python
-        uses: actions/setup-python@v1
+        uses: actions/setup-python@v2
         with:
           python-version: ${{ matrix.python-version }}
           architecture: x64