fix(sanitize): don't flag the shared gate's own public location - #4

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@v4, actions/setup-python@v5. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

This PR changes sanitize.config.json. The gate scanned it with the BASE branch's config; the change takes effect only after merge. A maintainer must review the config change by hand: anything that loosens the gate needs a reason.