Switch to maintained version of license-checker

[rugk]

You do use `https://github.com/mwittig/license-checker as a dependency.

However that is just a fork and – according to GitHub – 327 commits behind davglass:master (the upstream).

Upstream seems to be https://github.com/davglass/license-checker.

Could you please switch to the maintained upstream version? Thanks.

Because, somehow, the other fork is even giving me build errors, see rugk/emoji-mart-embed#4.

[rugk]

Described origin issue at #40

[mwittig]

@rugk Do you have git installed? If not, please install it on your system as it most likely will solve your installation issue as a work-around.

Switching to the maintained upstream version of license-checker is not that easy as the code-base have diverged a lot over time. I probably will replace the remaining bits used from license checker with my own implementation to get things sorted.

[rugk]

Of course, git is installed.