Update checkout action

Author: Cito

.github/workflows/release-docs.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2
     - name: Set up Python 3.7
       uses: actions/setup-python@v1
       with:

.github/workflows/test-package.yml

@@ -12,7 +12,7 @@ jobs:
         python-version: [3.6, 3.7, 3.8]
 
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2
     - name: Set up Python ${{ matrix.python-version }}
       uses: actions/setup-python@v1
       with: