Support listen 3.x

[twalpole]

Support listen 3.x and update travis config to match

[tdreyno]

👍

[saneshark]

👍

please update the dependency as this is affecting my ability use guard and terminal notifier with latest OSX.

[saneshark]

@kaizau is this something we could merge and bump versions on?

[bradgessler]

👍 running into this issue while trying to upgrade middleman to 4.x.

[tibastral]

Hey, could you merge this PR ? It's pretty useful !

Thank you very much !

[shehi]

This PR is very essential now, as our CI/CD routine became broken due to #150 . Please merge asap.

[pjg]

Any chance of maintainer to release a new version with this patch? The listen < 3.0 constrain is blocking a lot of gem upgrades (guard, celluloid).

[JakeBeresford]

This PR is essential to our projects use of fontcustom, please release a new version of the gem with this change ASAP!

[GesJeremie]

Time to merge guys!

[meowsus]

It would be amazingly helpful if this PR was merged @kaizau

[kaizau]

Apologies for the long hiatus, everyone. This little gem deserves more love and attention than I'm able to give.

Big thanks to @JakeBeresford for reaching out and offering to help. I've added him as a maintainer, and an update should be coming shortly.

[meowsus]

Big ups @JakeBeresford!

[AxelTheGerman]

Thanks @JakeBeresford for stepping up, and thanks @kaizau for all the work you have put in!