Change python-publish-test.yml, seems to be not dev but v2

Author: nschaetti

.github/workflows/python-publish-test.yml

@@ -13,9 +13,9 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@dev
+    - uses: actions/checkout@v2
     - name: Set up Python 3.8
-      uses: actions/setup-python@v1
+      uses: actions/setup-python@v2
       with:
         python-version: '3.8'
     - name: Install dependencies