chore: add packageManager to the manifest

[vecerek]

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Description

This change lets corepack take care of yarn version resolution so that contributors do not have to install and manage different yarn versions on their machines.

Related #735

Type of change

internal change related to tooling, a quality of life kind of improvement for contributors

Screenshots/Sandbox (if appropriate/relevant):

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How Has This Been Tested?

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Test Environment:

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• NodeJS:

Checklist:

• I have followed the
  CONTRIBUTING doc and the
  style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

Further comments

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Latest commit: 829f538

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[saihaj]

thanks!