build(deps): bump actions/checkout from 5 to 6 (#217)

Author: dependabot[bot]

.github/workflows/build.yml

@@ -11,7 +11,7 @@ jobs:
     env:
       IMAGE: 'ghcr.io/ustclug/hackergame:latest'
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
       with:
         fetch-depth: 0
     - name: Build Docker image

.github/workflows/smoketest.yml

@@ -16,7 +16,7 @@ jobs:
         # Debian 10 uses Python 3.7, which is not supported by Django 4.2 LTS
         python-version: [3.11, 3.9]
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
       with:
         fetch-depth: 0
     - name: Set up Python ${{ matrix.python-version }}