Update: Node engine requirements bumped to >=18 and some optionalDependencies packages bumped for security patches

[cahirodoherty-learningpool]

Fixes #3712

Update

• Node engine requirements bumped to >=18
• optionalDependencies packages bumped for security patches

[Copilot]

Pull Request Overview

This PR updates the Node.js engine requirement from >=16 to >=18 and bumps several optional imagemin dependencies to address security vulnerabilities. The changes also update the module import statements to use ES6 dynamic imports instead of CommonJS require statements.

• Node.js engine requirement increased to >=18 (breaking change)
• Updated four imagemin-related optional dependencies to newer major versions
• Modified import statements to use ES6 dynamic imports for imagemin packages

Reviewed Changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated 1 comment.

File	Description
package.json	Updates Node.js engine requirement and bumps imagemin optional dependencies
grunt/tasks/compress.js	Changes require statements to ES6 dynamic imports for imagemin modules

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[cahirodoherty-learningpool]

@oliverfoster The Breaking key word here will bump the package by a major version. This is the correct semantic approach in my opinion (as the underlying node engine requirement will potentially force client environment upgrades)
Previous references to "V6" will be outdated, but these seem to have stalled somewhat in any case. Any thought on this?

[oliverfoster]

https://docs.npmjs.com/cli/v11/configuring-npm/package-json#engines

I don't think it is necessary, unless the user has engine-strict enabled.

(v6 as it was, the bower > npm stuff is progressing, albeit slowly)