⬆️ Update actions/checkout action to v4 (#99)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/pytest.yml

@@ -11,7 +11,7 @@ jobs:
         python-version: ["3.8", "3.9", "3.10", "3.11", "3.12"]  # skip unsupported versions (3.7)
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - name: Set up Python ${{ matrix.python-version }}
         uses: actions/setup-python@v4
         with:

.github/workflows/release.yml

@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: Set up Python
       uses: actions/setup-python@v4
       with:

.github/workflows/update-readme.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Check out repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           persist-credentials: false
           fetch-depth: 0