Move development dependencies to Gemfile (#145)

Gemfile

@@ -1,4 +1,15 @@
 source "https://rubygems.org"
 
-# Specify your gem's dependencies in fx.gemspec
 gemspec
+
+gem "ammeter", ">= 1.1.3"
+gem "bundler", ">= 1.5"
+gem "database_cleaner"
+gem "pg"
+gem "pry"
+gem "rake"
+gem "redcarpet"
+gem "rspec", ">= 3.3"
+gem "standardrb"
+gem "yard"
+gem "warning"

fx.gemspec

@@ -24,18 +24,6 @@ Gem::Specification.new do |spec|
   spec.files = `git ls-files -z`.split("\x0")
   spec.require_paths = ["lib"]
 
-  spec.add_development_dependency "ammeter", ">= 1.1.3"
-  spec.add_development_dependency "bundler", ">= 1.5"
-  spec.add_development_dependency "database_cleaner"
-  spec.add_development_dependency "pg"
-  spec.add_development_dependency "pry"
-  spec.add_development_dependency "rake"
-  spec.add_development_dependency "redcarpet"
-  spec.add_development_dependency "rspec", ">= 3.3"
-  spec.add_development_dependency "standardrb"
-  spec.add_development_dependency "yard"
-  spec.add_development_dependency "warning"
-
   spec.add_dependency "activerecord", ">= 6.1"
   spec.add_dependency "railties", ">= 6.1"