deps(go/gateway): bump github.com/coreos/go-oidc/v3 from 3.11.0 to 3.21.0 in /services/gateway - #132

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/github-script@v7, actions/upload-artifact@v4. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/