Merge branch 'frozen-string-enable-spec-uploaders' into 'master'

spec/uploaders/attachment_uploader_spec.rb

spec/uploaders/avatar_uploader_spec.rb

spec/uploaders/external_diff_uploader_spec.rb

spec/uploaders/file_mover_spec.rb

spec/uploaders/file_uploader_spec.rb

spec/uploaders/gitlab_uploader_spec.rb

spec/uploaders/import_export_uploader_spec.rb

spec/uploaders/job_artifact_uploader_spec.rb

spec/uploaders/lfs_object_uploader_spec.rb

spec/uploaders/namespace_file_uploader_spec.rb

spec/uploaders/object_storage_spec.rb

spec/uploaders/personal_file_uploader_spec.rb

spec/uploaders/records_uploads_spec.rb

spec/uploaders/uploader_helper_spec.rb

...ers/workers/object_storage/background_move_worker_spec.rb

...ers/workers/object_storage/migrate_uploads_worker_spec.rb