Add support for Node 12, 14 & update dependencies

[StorytellerCZ]

Based on #38 I have added extended CI to cover Node 14 and removed CI for EOL Node versions. Mocha was also updated to the latest version.

[StorytellerCZ]

Still need to see if there is anything from #37 that can be ported over, but ready for review @jprichardson

[galenhuntington]

This PR looks great, but alas this project seems abandoned. The last mainline commit was 4.5 years ago.

[foysavas]

Happy to merge this, but don't have the ability publish to npm.

@StorytellerCZ can you update the README to point to recommend installing via @meteor/kexec or @StorytellerCZ/kexec and take over from there?

[jprichardson]

I'm happy to hand maintenance over. Need to know to whom.

[StorytellerCZ]

I'll ask the guys at Meteor if they could manage it since it is being used there.

[StorytellerCZ]

@jprichardson I can merge PRs and publish new versions, but I don't have the capacity to further develop.

[CMCDragonkai]

Any reason why this isn't merged yet?

[i-am-al-x]

@jprichardson please merge the pull request. Lots of us developers need "kexec" fixed, so that we can use WebPack with current version of Node. Your help is needed.

[jprichardson]

@i-am-al-x https://github.com/jprichardson/node-kexec/pull/40#issuecomment-841651984

[kedarv]

@i-am-al-x You can use the PR author's fork: https://github.com/StorytellerCZ/node-kexec and not have to be blocked on someone not hitting merge here :)