Merge branch 'frozen_spec_serializers' into 'master'

spec/serializers/analytics_build_entity_spec.rb

spec/serializers/analytics_build_serializer_spec.rb

spec/serializers/analytics_issue_entity_spec.rb

spec/serializers/analytics_issue_serializer_spec.rb

spec/serializers/analytics_merge_request_serializer_spec.rb

spec/serializers/analytics_stage_serializer_spec.rb

spec/serializers/analytics_summary_serializer_spec.rb

spec/serializers/blob_entity_spec.rb

spec/serializers/build_action_entity_spec.rb

spec/serializers/build_artifact_entity_spec.rb

spec/serializers/build_details_entity_spec.rb

spec/serializers/build_serializer_spec.rb

spec/serializers/cluster_application_entity_spec.rb

spec/serializers/cluster_basic_entity_spec.rb

spec/serializers/cluster_entity_spec.rb

spec/serializers/cluster_serializer_spec.rb

spec/serializers/commit_entity_spec.rb

spec/serializers/container_repository_entity_spec.rb

spec/serializers/container_tag_entity_spec.rb

spec/serializers/deploy_key_entity_spec.rb