ci: use action checkout v5

.github/workflows/continuous-integration.yml

@@ -41,7 +41,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
 
       - name: Check PR comment for flags
         if: ${{ github.event_name == 'pull_request' }}
@@ -77,7 +77,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
 
       - name: Test summary
         uses: ./.github/actions/test-summary
@@ -87,7 +87,7 @@ jobs:
     timeout-minutes: 5
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
 
       - name: REUSE Compliance Check
         uses: fsfe/reuse-action@v5
@@ -99,7 +99,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
 
       - name: Lint Checker
         uses: ./.github/actions/lint-clang