Updated gemspec to rails 6, ran bundle update

[bayornet]

Trying to upgrade Sparkle to rails 6:

bundle update rails
Ignoring eventmachine-1.0.9.1 because its extensions are not built. Try: gem pristine eventmachine --version 1.0.9.1
Ignoring thin-1.5.1 because its extensions are not built. Try: gem pristine thin --version 1.5.1
Fetching gem metadata from https://rubygems.org/.......
Resolving dependencies...
Could not find compatible versions

Because every version of laforge depends on rails ~> 5.0
  and Gemfile depends on rails ~> 6.0,
  laforge cannot be used.
So, because Gemfile depends on laforge >= 0,
  version solving has failed.