Add expire_at to PipelineArtifact

This new column will be used to expire
artifact in order to limit the storage capacity.

changelogs/unreleased/mo-add-expire-at-to-pipeline-artifact.yml

+---
+title: Add expire_at to PipelineArtifact
+merge_request: 39114
+author:
+type: fixed

db/migrate/20200810152043_add_expire_at_to_ci_pipeline_artifact.rb

+# frozen_string_literal: true
+
+class AddExpireAtToCiPipelineArtifact < ActiveRecord::Migration[6.0]
+  DOWNTIME = false
+
+  def change
+    add_column :ci_pipeline_artifacts, :expire_at, :datetime_with_timezone
+  end
+end

db/schema_migrations/20200810152043

+d459b160ae86f035509e382c12b76fdd441f58e0838a983471326a750a48e9fd
\ No newline at end of file

db/structure.sql

@@ -10058,6 +10058,7 @@ CREATE TABLE public.ci_pipeline_artifacts (
     file_type smallint NOT NULL,
     file_format smallint NOT NULL,
     file text,
+    expire_at timestamp with time zone,
     CONSTRAINT check_191b5850ec CHECK ((char_length(file) <= 255))
 );