Fix Dependabot by removing npm engine-strict=true

[colinrotherham]

The Node.js LTS v20 update in #4201 has stopped Dependabot from running

Rather than allow Node.js v18 and npm v9.6.5 we can remove engine-strict=true

Dependabot uses Node.js v18.18.2
 and NPM 9.6.5
. Due to the engine-strict setting, the update will not succeed.

Other options considered

1. Wait for Dependabot to update to Node.js v20
   But we'd still be blocked by Node.js v20 using npm@10.1.0

2. Update package.json to support Node.js v18 (and npm v9.6.5)

     "engines": {
   -   "node": "^20.9.0",
   -   "npm": "^10.1.0"
   +   "node": "^18.12.0 || ^20.9.0",
   +   "npm": "^9.1.0 || ^10.1.0"
     },

[github-actions]

📋 Stats

File sizes

File	Size
dist/govuk-frontend-5.0.0-beta.0.min.css	114 KiB
dist/govuk-frontend-5.0.0-beta.0.min.js	37.85 KiB
packages/govuk-frontend/dist/govuk/all.bundle.js	77.08 KiB
packages/govuk-frontend/dist/govuk/all.bundle.mjs	72.37 KiB
packages/govuk-frontend/dist/govuk/all.mjs	3.8 KiB
packages/govuk-frontend/dist/govuk/govuk-frontend-component.mjs	359 B
packages/govuk-frontend/dist/govuk/govuk-frontend.min.css	113.99 KiB
packages/govuk-frontend/dist/govuk/govuk-frontend.min.js	37.92 KiB
packages/govuk-frontend/dist/govuk/i18n.mjs	5.3 KiB

Modules

File	Size
all.mjs	68.7 KiB
components/accordion/accordion.mjs	21.35 KiB
components/button/button.mjs	4.48 KiB
components/character-count/character-count.mjs	20.79 KiB
components/checkboxes/checkboxes.mjs	5.61 KiB
components/error-summary/error-summary.mjs	5.79 KiB
components/exit-this-page/exit-this-page.mjs	15.79 KiB
components/header/header.mjs	3.68 KiB
components/notification-banner/notification-banner.mjs	4.32 KiB
components/radios/radios.mjs	4.6 KiB
components/skip-link/skip-link.mjs	3.6 KiB
components/tabs/tabs.mjs	9.37 KiB

View stats and visualisations on the review app

---

Action run for 55c8e9f