ci: pass GITHUB_TOKEN to stats script step

[nice2mitja]

Summary

Adds GITHUB_TOKEN as an env variable to the Python step that runs fetch_and_append_stats.py from the release_stats branch.

Why

The companion PR #77 (against release_stats) switches that script to GitHub's GraphQL API, which is the only way to work around the /repos/.../releases REST endpoint's hard ~1000-result pagination cap. The cap was causing the oldest releases (e.g. sapmachine-11.0.2 with 1.94 M downloads) to silently fall out of the snapshots.

GraphQL requires authentication. The workflow must therefore pass GITHUB_TOKEN to the script's environment.

Diff

    # 6. Run the Python script to fetch and append download stats
    - name: Run Python script to fetch and append download stats
+     env:
+       GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
      run: python .github/scripts/fetch_and_append_stats.py

That's the entire change.

Merge order

This PR is forward-compatible with the current script (an unused env var is harmless), so it can be merged at any time — ideally before #77, so that when the script update lands the workflow already has the env var ready.

Related

• fix(stats): switch to GraphQL API to capture all releases #77 — switches fetch_and_append_stats.py to GraphQL (against release_stats branch)