chore(deps): bump gradle-wrapper from 8.6 to 9.6.0 in /firestore - #2277

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, Makeshift/generate-dependabot-glob-action@master, peter-evans/create-pull-request@v6. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/