ci: change contents permission to write for release notes API

The GitHub API releases/generate-notes endpoint requires contents: write
permission, not just contents: read. This fixes HTTP 403 errors in tests
that generate release notes.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: cgrindel

.github/workflows/ci.yml

@@ -17,7 +17,7 @@ concurrency:
   group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
   cancel-in-progress: true
 permissions:
-  contents: read
+  contents: write
   pull-requests: read
 jobs:
   all_ci_tests: