workaround: @oclif/core in @oclif/plugins-plugin@^2.x is not compatible with node-14

[shazron]

Closes #466

Motivation and Context

Make every PR pass again.

How Has This Been Tested?

the CI is the test.
manually tested also.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have signed the Adobe Open Source CLA.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[codecov]

Codecov Report

Merging #468 (bd258b2) into master (d710269) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##            master      #468   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            5         5           
  Lines          238       238           
  Branches        47        47           
=========================================
  Hits           238       238           

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[shazron]

Turns out npm ci has issues with the overrides key in package.json 😭 npm/cli#4942 (npm install is fine)