🎨 Standarize code ./ directory

Author: WaKeMaTTa

Gemfile

@@ -1,10 +1,10 @@
-source 'https://rubygems.org'
+source "https://rubygems.org"
 
-#main gemspec
-gemspec :name => 'nmatrix'
+# main gemspec
+gemspec name: "nmatrix"
 
-#plugin gemspecs
-Dir['nmatrix-*.gemspec'].each do |gemspec_file|
+# plugin gemspecs
+Dir["nmatrix-*.gemspec"].each do |gemspec_file|
   plugin_name = gemspec_file.match(/(nmatrix-.*)\.gemspec/)[1]
-  gemspec(:name => plugin_name, :development_group => :plugin)
+  gemspec(name: plugin_name, development_group: :plugin)
 end