fix: allow protected files in create-pull-request safe output

package.json, pnpm-lock.yaml, and .github/template-sync-state.json are
protected by default. Since this workflow explicitly manages these files,
set protected-files: allowed.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: Alexandre Nédélec

.github/workflows/template-sync.lock.yml

@@ -19,6 +19,7 @@ tools:
 
 safe-outputs:
   create-pull-request:
+    protected-files: allowed
 ---
 
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