Bump CI actions/checkout version

Author: basil-conto

.github/workflows/build.yml

@@ -44,7 +44,7 @@ jobs:
           - release-snapshot
           - snapshot
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
       with:
         persist-credentials: false
     - uses: purcell/setup-emacs@master