Restore doc-bundle uploads in sync workflow (#74)

The sync job declared no permissions and relied on the default
GITHUB_TOKEN, so gh release upload returned HTTP 403 and new doc
bundles stopped being published.

Declare explicit least-privilege permissions matching release.yml:
top-level permissions {} plus contents: write on the sync job, which
reads the release assets and uploads the bundle.

Author: inancgumus

.github/workflows/sync.yml

@@ -5,9 +5,13 @@ on:
     - cron: '3 */3 * * *'
   workflow_dispatch:
 
+permissions: {}
+
 jobs:
   sync:
     runs-on: ubuntu-latest
+    permissions:
+      contents: write
     steps:
       - uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
       - uses: actions/setup-go@40f1582b2485089dde7abd97c1529aa768e1baff # v5.6.0