chore(deps): update actions/checkout action to v6

Author: renovate[bot]

.github/workflows/build.yml

@@ -27,7 +27,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Set up Go
         uses: actions/setup-go@v5

.github/workflows/cleanup.yml

@@ -16,7 +16,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Cleanup
         run: |