Ruby: fix linter errors

Gemfile

@@ -1,8 +1,10 @@
-source 'https://rubygems.org'
-gem 'nanoc', '~> 4.12'
-gem 'nanoc-live', '~> 1.0'
-gem 'rainpress', '~> 1.0'
-gem 'sass'
-gem 'standardrb'
+# frozen_string_literal: true
+
+source "https://rubygems.org"
+gem "nanoc", "~> 4.12"
+gem "nanoc-live", "~> 1.0"
+gem "rainpress", "~> 1.0"
+gem "sass"
+gem "standardrb"
 gem "ryo.rb"
 gem "paint"

Rakefile.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require "bundler/setup"
 require_relative "lib/tasks"
 include Tasks

Rules

@@ -50,4 +50,4 @@ compile "/images/*" do
 end
 
 compile("/**/*") { write(nil) }
-layout('**/*', :erb)
+layout("**/*", :erb)

lib/rake/cmd.rb

@@ -1,14 +1,15 @@
+# frozen_string_literal: true
+
 module Cmd
   def cmd(cmd, *args, silent: false)
     print "  -> #{cmd}: " unless silent
     _, result = Process.wait2 Process.spawn(
       [cmd, cmd],
       *args,
-      STDERR=>File::NULL,
-      STDOUT=>File::NULL
+      $stderr => File::NULL,
+      $stdout => File::NULL
     )
-    case
-    when result.success?
+    if result.success?
       print Paint["OK", :green, :bold], "\n" unless silent
     else
       print Paint["ERROR", :red, :bold], "\n" unless silent

lib/tasks/deploy.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Tasks::Deploy
   require_relative "deploy/local"
 end