[18.0][FIX] sale_margin_pricelist_computation: Use sale.order.line _get_margin_pricelist_eval_context to test pricelist.item eval context - #278

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, actions/setup-python@v5. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/