build(deps): bump actions/checkout from 3 to 4 (#138)

.github/workflows/python.yml

@@ -17,7 +17,7 @@ jobs:
       matrix:
         python-version: ['3.9']
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - uses: actions/setup-python@v4
       with:
         python-version: ${{ matrix.python-version }}
@@ -40,7 +40,7 @@ jobs:
         - '3.11'
       fail-fast: false
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - uses: actions/setup-python@v4
       with:
         python-version: ${{ matrix.python-version }}
@@ -74,7 +74,7 @@ jobs:
   install:
     runs-on: ubuntu-20.04
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - uses: actions/setup-python@v4
       with: {python-version: 3.9}
     - run: '! ical2vdir --help'
@@ -88,7 +88,7 @@ jobs:
       matrix:
         python-version: ['3.9']
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - uses: actions/setup-python@v4
       with:
         python-version: ${{ matrix.python-version }}