Bump actions/checkout from 5 to 6 (#53)

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/build.yml

@@ -11,7 +11,7 @@ jobs:
   deploy-book:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
 
     # Install dependencies
     - name: Set up Python 3.12