Replace engines.npm with packageManager

[jackdomleo7]

Description

• Resolve issue where consuming projects displayed a warning if they were not using npm 9. npm 9 is just the package manager being used within the project, consuming projects do not require it.

Why is this important?

• False warnings are not good

Covered test cases

N/A

Did you test on all major browsers?

• Chrome
• Firefox
• Edge
• Safari

Other details

N/A

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T&Cs

• I confirm I have read and understand the contributing guidelines
• I understand the work in this pull request will not be released straight away and will appear in a future release (if approved)
• I confirm the work in this pull request is true and valid to the best of my knowledge
• I have updated the README, features.md and codes.md files where applicable