fix(gha): bump deprecated action(s) in .github/workflows/linters.yml to resolve Node.js warnings [NO JIRA]

[g2-enterprise-platform-bot]

Why

GitHub Actions runners are dropping Node.js 20 (removal 2026-09-16). These action versions target a deprecated Node runtime and were flagged by the gha-annotation-monitor Datadog source in the last 25h.

Changes

• .github/workflows/linters.yml: actions/checkout@v2 → actions/checkout@v7 (compare)

Detection

Datadog Logs query (last 25h):

source:gha-annotation-monitor @raw_message:*Node.js*deprecated*

Tracking

Multica issue DX-82 — GHA Node.js deprecation fix — 2026-08-05 (automated daily scan).

Conventions: repo has no AGENTS.md/CLAUDE.md/CONTRIBUTING.md conventions for PR format.
Reviewers: @wheeyls, @dknox20

Opened as a draft by the Lifecycle Manager autopilot. Promoted to ready-for-review automatically once CI is clean.

[g2-enterprise-platform-bot]

CI check build (2.7.8, rails_6.1), build (3.1.6, rails_6.1), build (3.0.7, rails_6.1), build (3.0.7, rails_7.0), build (3.1.6, rails_7.0), build (3.1.6, rails_7.1), build (3.2.5, rails_6.1), build (2.7.8, rails_7.1), build (2.7.8, rails_7.0), build (3.2.5, rails_7.0) regressed on this bump — keeping as draft for human review