Request: Version bump

[ghost]

When an official Middleman extension has a version number in the 3.x range, it does to me imply that the extension is primarily intended for / tested against Middleman 3.x

Next, best as I can tell, Middleman-Minify-HTML currently uses htmlcompressor 0.2, and not the newer 0.3 release.

Could we maybe have a new release of this gem, with a version bump to 4.x and/or explicit mention of Middleman 4 support, and with the newer htmlcompressor 0.3included?

Thank you for your consideration. 😄

[tdreyno]

I, personally, don't have the availability to work on this. But if you, or anyone with time, can make that PR and the tests still pass, I'll merge it.

Regarding the version number, no, the gem version should be unrelated to the MM it supports (that's mentioned in the gemspec). I believe this gem works with MM 3 and 4.