Rails 4.2 - actionamailer

[rogermingorance]

We can not update to rails 4.2 becuase of the dependency on 'actionmailer' gem:
$ bundle update rails
Fetching gem metadata from https://rubygems.org/.........
Resolving dependencies...
Bundler could not find compatible versions for gem "actionmailer":
In Gemfile:
slim-rails (>= 0) ruby depends on
actionmailer (< 4.2, >= 3.0) ruby

rails (= 4.2.0) ruby depends on
actionmailer (4.2.0)

[minad]

should be fixed in newest version