Update release.yml

Author: VaghinakDev

.github/workflows/release.yml

@@ -9,7 +9,7 @@ jobs:
     name: Build and publish Python 🐍 distributions 📦 to PyPI and TestPyPI
     runs-on: ubuntu-18.04
     steps:
-    - uses: actions/checkout@master
+    - uses: actions/checkout@v2
     - name: Set up Python
       uses: actions/setup-python@v1
       with: