Update actions/checkout action to v5

Author: renovate[bot]

.github/workflows/ci.yml

@@ -10,7 +10,7 @@ jobs:
       matrix:
         python-version: [3.6, 3.7, 3.8, 3.9]
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v5
     - name: Set up Python ${{ matrix.python-version }}
       uses: actions/setup-python@v2
       with:

.github/workflows/release.yml

@@ -12,7 +12,7 @@ jobs:
       matrix:
         python-version: [3.9]
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v5
     - name: Set up Python ${{ matrix.python-version }}
       uses: actions/setup-python@v2
       with: