Migrate to use nyc from istanbul

Upon installing, this shows up:

warning karma-coverage > istanbul@0.4.5: 
This module is no longer maintained, try this instead:
  npm i nyc

Would it be possible to move to use nyc instead of istanbul?

[Aaronius]

When I install karma-coverage 2.0.1, I’m still seeing:

npm WARN deprecated istanbul@0.4.5: This module is no longer maintained, try this instead:
npm WARN deprecated   npm i nyc
npm WARN deprecated Visit https://istanbul.js.org/integrations for other alternatives.

If I run npm ls istanbul, I see the following:

@adobe/alloy@0.0.1-alpha.8 /Users/aahardy/dev/alloy
└─┬ karma-coverage@2.0.1
  └── istanbul@0.4.5 

and in package-lock.json, I see:

    "karma-coverage": {
      "version": "2.0.1",
      "resolved": "https://registry.npmjs.org/karma-coverage/-/karma-coverage-2.0.1.tgz",
      "integrity": "sha512-SnFkHsnLsaXfxkey51rRN9JDLAEKYW2Lb0qOEvcruukk0NkSNDkjobNDZPt9Ni3kIhLZkLtpGOz661hN7OaZvQ==",
      "dev": true,
      "requires": {
        "dateformat": "^1.0.6",
        "istanbul": "^0.4.0",
        "istanbul-lib-coverage": "^2.0.5",
        "istanbul-lib-instrument": "^3.3.0",
        "istanbul-lib-report": "^2.0.8",
        "istanbul-lib-source-maps": "^3.0.6",
        "istanbul-reports": "^2.2.4",
        "lodash": "^4.17.11",
        "minimatch": "^3.0.0",
        "source-map": "^0.5.1"
      }
    },

I’m not sure why istanbul is marked as required there.

[dogoku]

Is there any work in progress to migrate to use nyc?

PR #377 has already done the work, it just needs to be released