build(deps): bump actions/checkout from 5 to 6 in the official-actions group (#3439)

.github/workflows/decnum.yml

@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-24.04
     steps:
       - name: Clone repository
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           submodules: true
       - name: Install packages