Move rails-assets gems to own source block

Gemfile

@@ -1,5 +1,6 @@
+# frozen_string_literal: true
+
 source 'https://rubygems.org'
-source 'https://rails-assets.org'
 
 gem 'rails', '~> 5.2'
 gem 'rails-i18n', '~> 5.0'
@@ -30,8 +31,6 @@ gem 'bootstrap_form'
 gem 'font-kit-rails'
 gem 'nprogress-rails'
 gem 'font-awesome-rails', '~> 4.7.0'
-gem 'rails-assets-growl'
-gem 'rails-assets-jquery', '~> 2.2.0'
 gem "paperclip", "~> 4.2"
 gem 'delayed_paperclip'
 gem 'fog-core'
@@ -43,6 +42,11 @@ gem 'tiny-color-rails'
 gem 'jquery-minicolors-rails'
 gem 'colorize'
 
+source "https://rails-assets.org" do
+  gem 'rails-assets-growl'
+  gem 'rails-assets-jquery', '~> 2.2.0'
+end
+
 gem 'ruby-progressbar'
 
 gem 'rails_admin'

Gemfile.lock

@@ -571,8 +571,8 @@ DEPENDENCIES
   puma
   questiongenerator!
   rails (~> 5.2)
-  rails-assets-growl
-  rails-assets-jquery (~> 2.2.0)
+  rails-assets-growl!
+  rails-assets-jquery (~> 2.2.0)!
   rails-i18n (~> 5.0)
   rails_admin
   rake