BC: drop support for `node<18`

[jkowalleck]

node < 18 is no longer maintained. see https://github.com/nodejs/release#release-schedule

lets drop support for node < 18

idea:

• Support node versions greater equal last active release -- so that all implemented features are included, and maintenance releases are compatible
• and so on

(this might enable more up-to-date developer experience, and updates in some [dev-]dependencies)

[jkowalleck]

reminder: remove unused cases and the whole usage of npm_config_engine_strict=false in the workflows https://github.com/CycloneDX/cyclonedx-javascript-library/blob/d17c4b1425babae8ab12a456caf821e25f5c1420/.github/workflows/nodejs.yml#L184-L217