Update g_forest() to support col_x and col_ci in the same column. - #1507

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: contributor-assistant/github-action@9340315624c6e16cef1f2c63bdeb0f0c49c6f474. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/