Update SDK to 26.16.0 - #19

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/cache@v4, actions/checkout@v4, docker/login-action@v3, google-github-actions/auth@v1, hoverkraft-tech/compose-action@v2.0.2, shivammathur/setup-php@2.31.1. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/