It seems like upcoming CocoaPods require activesupport > 5 which is in conflict with slather.
Bundler could not find compatible versions for gem "activesupport":
In Gemfile:
cocoapods (= 1.10.0.beta.1) was resolved to 1.10.0.beta.1, which depends on
activesupport (> 5)
slather (~> 2.4.9) was resolved to 2.4.9, which depends on
activesupport (< 5, >= 4.0.2)
Similar to #464.
It seems like upcoming CocoaPods require
activesupport > 5
which is in conflict with slather.