Replace awesome print with amazing print

Amazing Print is a fork of Awesome Print that has already resolved
the undefined method marshal_dump for ActiveModel::Errors issue [1].

---

[1]: awesome-print/awesome_print#413

README.md

@@ -43,7 +43,7 @@ And then execute:
 5. Create a new Pull Request
 
 [pry]:                http://pry.github.com
-[awesome_print]:      https://github.com/michaeldv/awesome_print
+[amazing_print]:      https://github.com/amazing-print/amazing_print
 [pry-rails]:          https://github.com/rweng/pry-rails
 [pry-doc]:            https://github.com/pry/pry-doc
 [pry-byebug]:         https://github.com/deivid-rodriguez/pry-byebug

dev_tools.gemspec

@@ -24,7 +24,7 @@ Gem::Specification.new do |spec|
   spec.add_runtime_dependency 'pry-rails'
   spec.add_runtime_dependency 'pry-byebug'
   spec.add_runtime_dependency 'pry-doc'
-  spec.add_runtime_dependency 'awesome_print'
+  spec.add_runtime_dependency 'amazing_print'
   spec.add_runtime_dependency 'letter_opener'
   spec.add_runtime_dependency 'dotenv-rails'
   spec.add_runtime_dependency 'rubocop'