fix: downgrade @oclif/plugin-help to ^2.2.3

[shazron]

The help plugin, or one of its sub-dependencies, is breaking the tests in node-16 (since 7 days ago: see Actions tab daily tests which uses node-16). Tests pass on node-14. It's possible that the help plugin on v3+ does not work on node-16. Downgrading the plugin to v2 fixes this.

Closes #27

How Has This Been Tested?

1. npm test
2. linking the plugin at this branch and running aio event does not show the TypeError: Help is not a constructor error

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 #28 (7a1baac) into master (99b7b5a) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##            master       #28   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           21        21           
  Lines          483       499   +16     
  Branches        48        64   +16     
=========================================
+ Hits           483       499   +16     

Impacted Files	Coverage Δ
src/commands/event/provider/get.js	100.00% <0.00%> (ø)
src/commands/event/provider/list.js	100.00% <0.00%> (ø)
src/commands/event/provider/create.js	100.00% <0.00%> (ø)
src/commands/event/provider/delete.js	100.00% <0.00%> (ø)
src/commands/event/provider/update.js	100.00% <0.00%> (ø)
src/commands/event/registration/get.js	100.00% <0.00%> (ø)
src/commands/event/eventmetadata/get.js	100.00% <0.00%> (ø)
src/commands/event/registration/list.js	100.00% <0.00%> (ø)
src/commands/event/eventmetadata/list.js	100.00% <0.00%> (ø)
src/commands/event/registration/create.js	100.00% <0.00%> (ø)
... and 4 more

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[fe-lix-]

Tested and it works.