Update actions/checkout action to v6

Author: renovate[bot]

.github/workflows/gen_data.yaml

@@ -20,7 +20,7 @@ jobs:
 
       steps:
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           path: main
           fetch-depth: 1

.github/workflows/schedule_builds.yaml

@@ -49,7 +49,7 @@ jobs:
         continue-on-error: false
 
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           path: main
           fetch-depth: 1

.github/workflows/sync_lists.yaml

@@ -17,7 +17,7 @@ jobs:
 
       steps:
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           path: main
           fetch-depth: 1