Update dependency commander to v6

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
commander	dependencies	major	~5.1.0 -> ~6.0.0

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Release Notes

tj/commander.js

v6.0.0

Compare Source

Added

• add support for variadic options ([#​1250])
• allow options to be added with just a short flag ([#​1256])
  • Breaking the option property has same case as flag. e.g. flag -n accessed as opts().n (previously uppercase)
• Breaking throw an error if there might be a clash between option name and a Command property, with advice on how to resolve ([#​1275])

Fixed

• Options which contain -no- in the middle of the option flag should not be treated as negatable. ([#​1301])

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[codecov]

Codecov Report

Merging #259 into master will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##            master      #259   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            2         2           
  Lines          131       131           
=========================================
  Hits           131       131           

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