inaccurate relative path in packages/react-scripts/lib/createJestConfig.js

[snyderpa]

See line 14 of https://github.com/constfun/create-react-WebExtension/blob/master/packages/react-scripts/lib/createJestConfig.js

When running npm test the following output is generated:

> extension@0.1.0 test /Users/psnyder/georgesagent/bitbucket/georgesagent/src/extension
> react-scripts-web-ext test --env=jsdom

module.js:538
    throw err;
    ^

Error: Cannot find module '../../config/paths'
    at Function.Module._resolveFilename (module.js:536:15)
    at Function.Module._load (module.js:466:25)
    at Module.require (module.js:579:17)
    at require (internal/module.js:11:18)
    at Object.<anonymous> (/Users/psnyder/georgesagent/bitbucket/blah/src/extension/node_modules/react-scripts-webextension/lib/createJestConfig.js:14:15)
    at Module._compile (module.js:635:30)
    at Object.Module._extensions..js (module.js:646:10)
    at Module.load (module.js:554:32)
    at tryModuleLoad (module.js:497:12)
    at Function.Module._load (module.js:489:3)
npm ERR! Test failed.  See above for more details.

It looks like the target is in a sibling folder at ../config/paths