Make Rubocop happy

db/migrate/20190510055357_migrate_steam_auth_data.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class MigrateSteamAuthData < ActiveRecord::Migration[5.2]
   def up
     execute <<~SQL

lib/auth/steam_authenticator.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Auth::SteamAuthenticator < ::Auth::ManagedAuthenticator
   def name
     'steam'

lib/validators/enable_steam_logins_validator.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class EnableSteamLoginsValidator
   def initialize(opts = {})
     @opts = opts

plugin.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # name: Steam authentication with Discourse
 # about: Authenticate with Discourse with Steam
 # version: 2.0.1