upgrade to lodash required according to 'npm audit'

[moribellamy]

https://www.npmjs.com/advisories/1065

currently at head we are pinned to 4.17.11, https://github.com/mozilla/web-ext/blob/master/package-lock.json#L31

[ghost]

I think this requires an update to fx-runner.

└─┬ web-ext@3.1.0
  └─┬ fx-runner@1.0.10
    └── lodash@4.17.11 

Why are all these projects using exact versions of their dependencies? Wouldn't it be better to use "~4.17.11" or "^4.17.11"?

[raulrpearson]

I added an issue to the fx-runner repo.