Merge branch 'frozen-string-enable-lib-gitlab-grape' into 'master'

Enable frozen string for grape logging specs

See merge request gitlab-org/gitlab!20596

spec/lib/gitlab/grape_logging/loggers/exception_logger_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Gitlab::GrapeLogging::Loggers::ExceptionLogger do

spec/lib/gitlab/grape_logging/loggers/queue_duration_logger_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Gitlab::GrapeLogging::Loggers::QueueDurationLogger do