Drop persist-credentials in Pages workflow

peaceiris/actions-gh-pages uses its own `github_token` input for the
push to gh-pages; the credentials persisted by `actions/checkout`
aren't read. Setting `persist-credentials: false` matches the rest of
the workflows in this repo and silences zizmor's `artipacked` rule.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: oschwald

.github/workflows/pages.yml

@@ -19,7 +19,7 @@ jobs:
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
         with:
-          persist-credentials: true
+          persist-credentials: false
 
       - name: Setup mise
         uses: jdx/mise-action@6d1e696aa24c1aa1bcc1adea0212707c71ab78a8 # v3.6.1