Fixed Rubocop deprecation warnings

app/services/projects/update_pages_service.rb

@@ -25,7 +25,7 @@ module Projects
 
         # Check if we did extract public directory
         archive_public_path = File.join(archive_path, 'public')
-        raise 'pages miss the public folder' unless Dir.exists?(archive_public_path)
+        raise 'pages miss the public folder' unless Dir.exist?(archive_public_path)
         raise 'pages are outdated' unless latest?
 
         deploy_page!(archive_public_path)

lib/gitlab/geo/update_queue.rb

@@ -88,7 +88,7 @@ module Gitlab
       def self.redis_connection
         redis_config_file = Rails.root.join('config', 'resque.yml')
 
-        redis_url_string = if File.exists?(redis_config_file)
+        redis_url_string = if File.exist?(redis_config_file)
                              YAML.load_file(redis_config_file)[Rails.env]
                            else
                              'redis://localhost:6379'

spec/services/projects/update_pages_service_spec.rb

@@ -18,7 +18,7 @@ describe Projects::UpdatePagesService do
       let(:empty_file) { fixture_file_upload(Rails.root + "spec/fixtures/pages_empty.#{format}") }
       let(:metadata) do
         filename = Rails.root + "spec/fixtures/pages.#{format}.meta"
-        fixture_file_upload(filename) if File.exists?(filename)
+        fixture_file_upload(filename) if File.exist?(filename)
       end
 
       before do