[CI]: outdated CI (Node.js 25 & actions/*) workflows

[MikeMcC399]

Situation

CI tests in .github workflows are currently running by default under Node.js 25.6, which reached end-of-life at the beginning of June 2026, and they are using deprecated GitHub Actions actions/checkout@v4, actions/setup-node@v4, etc., that run on node20 (also end-of-life).

berry/.github/actions/prepare/action.yml

Lines 6 to 9 in 2f45268

	node-version:
	description: 'The version of Node.js to use'
	required: false
	default: '25.6'

Node.js 25 entered end-of-life on 2026-06-01

Workflow logs, such as https://github.com/yarnpkg/berry/actions/workflows/e2e-webpack-workflow.yml, show annotations:

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-node@v4. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

Suggestion

• Update to default Node.js 26
• Update JavaScript GitHub Actions to current versions