Fix authMethod default not stored in auth options (AO2) - #2313

Input required and not supplied: server-auth

Process completed with exit code 2.

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: ably/test-observability-action@5b61d9c59f356b83426cab1b8243dd8bf03c1bea, actions/checkout@ee0669bd1cc54295c223e0bb666b733df41de1c5, actions/setup-node@f1f314fca9dfce2769ece7d933488f076716723e. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/