dependency with gems that are not required

[tamiradari]

Both rb-fsevent and rb-inotify are in the dependency in listen-3.7.1.gemspec.
But:

• For Linux only rb-inotify is required.
• For Darwin (OSX) only rb-fsevent is required.
• For Windows, none of them is required (WDM can be added).

[ColinDKelley]

@tamiradari These are good points.

Could you possibly submit a PR that makes these dependencies conditional?

[uvlad7]

It's easy to make them conditional, but you'll need to publish separate OS-specific versions of the gem

[ColinDKelley]

If anyone is inspired to make a PR that breaks out to OS-specific versions, please do!