I recently tried to update to Rails 5 and it won't seem to work. I switched it over in my gemfile from 4.2.6 and deleted the gemfile.lock. I then ran
gem update rails
Bundler could not find compatible versions for gem "rails":
rails (= 5.0.0)
devise-heroku was resolved to 0.1.0, which depends on
rails (>= 3.1.1)
interactor-rails (~> 1.0) was resolved to 1.0.0, which depends on
rails (< 5, >= 3)
So, from the output you got, interactor-rails 1.0 does not support Rails 5. I checked out their page, and it looks like you need to bundle 2.0 version of that gem.
gem "interactor-rails", "~> 2.0"
You can read the docs here
You might need to upgrade the devise-heroku gem as well.