title: PG::UndefinedTable: ERROR: relation "active_storage_blobs" does not exist
body: <p>Updated app Rails 5.2 to 6, the following two migrations were added by the update:</p>
  
  <pre><code>    # This migration comes from active_storage (originally 20190112182829)
      class AddServiceNameToActiveStorageBlobs &lt; ActiveRecord::Migration[6.0]
    def up
      unless column_exists?(:active_storage_blobs, :service_name)
        add_column :active_storage_blobs, :service_name, :string
  
        if configured_service = ActiveStorage::Blob.service.name
          ActiveStorage::Blob.unscoped.update_all(service_name: configured_service)
        end
  
        change_column :active_storage_blobs, :service_name, :string, null: false
      end
    end
  end
  </code></pre>
  
  <p>and </p>
  
  <pre><code># This migration comes from active_storage (originally 20191206030411)
  class CreateActiveStorageVariantRecords &lt; ActiveRecord::Migration[6.0]
    def up
      create_table :active_storage_variant_records do |t|
        t.belongs_to :blob, null: false, index: false
        t.string :variation_digest, null: false
  
        t.index %i[ blob_id variation_digest ], name: "index_active_storage_variant_records_uniqueness", unique: true
        t.foreign_key :active_storage_blobs, column: :blob_id
      end
    end
  end
  </code></pre>
  
  <p>trying to run the migrations gives the me error on the title. Haven't found anything online, any ideas on how to fix it?</p>