Add severity_levels into approval_project_rules

Changelog: added

db/migrate/20210726202748_add_vulnerability_severities_into_approval_project_rules.rb

+# frozen_string_literal: true
+
+class AddVulnerabilitySeveritiesIntoApprovalProjectRules < ActiveRecord::Migration[6.1]
+  def up
+    add_column :approval_project_rules, :severity_levels, :text, array: true, null: false, default: []
+  end
+
+  def down
+    remove_column :approval_project_rules, :severity_levels
+  end
+end

db/schema_migrations/20210726202748

+378e12c3c7c49e294ab4ab792151af8e3829cc6f38295d5faa0995ad16f3f934
\ No newline at end of file

db/structure.sql

@@ -9729,7 +9729,8 @@ CREATE TABLE approval_project_rules (
     name character varying NOT NULL,
     rule_type smallint DEFAULT 0 NOT NULL,
     scanners text[],
-    vulnerabilities_allowed smallint
+    vulnerabilities_allowed smallint,
+    severity_levels text[] DEFAULT '{}'::text[] NOT NULL
 );
 
 CREATE TABLE approval_project_rules_groups (