Keep rubocop happy with the new Selenium runner

ci/qunit-selenium-runner.rb

@@ -1,9 +1,11 @@
-require 'qunit/selenium/test_runner'
-require 'chromedriver/helper'
+# frozen_string_literal: true
+
+require "qunit/selenium/test_runner"
+require "chromedriver/helper"
 
 driver_options = Selenium::WebDriver::Chrome::Options.new
-driver_options.add_argument('--headless')
-driver_options.add_argument('--disable-gpu')
+driver_options.add_argument("--headless")
+driver_options.add_argument("--disable-gpu")
 
 driver = ::Selenium::WebDriver.for(:chrome, options: driver_options)
 result = QUnit::Selenium::TestRunner.new(driver).open(ARGV[0], timeout: 60)