Require Node.js 6?

[realityking]

I've been looking into updating several packages to reduce the amount of duplication in a typical imagemin installation, right now it's a bit all over the place.

I noticed some of the packages far down the tree are already requiring Node.js 6, e.g. import-lazy, is-jpg and semver-regex.

Should imagemin + plugins move to Node.js 6 as the min. required version?

I'm happy to put the leg work in for this.

[sindresorhus]

Yes, we should drop Node.js 4 in all the modules. Help would be much appreciated.