drupal/core/modules/migrate/migrate.install

<?php

/**
 * @file
 * Contains install and update functions for Migrate.
 */

/**
 * Implements hook_update_last_removed().
 */
function migrate_update_last_removed() {
  return 8001;
}

/**
 * Remove the year 2038 date limitation.
 */
function migrate_update_10100(&$sandbox = NULL) {
  $connection = \Drupal::database();
  $tables = $connection->schema()->findTables('migrate_map_%');
  if (!empty($tables) && $connection->databaseType() != 'sqlite') {
    foreach ($tables as $table) {
      $new = [
        'type' => 'int',
        'unsigned' => TRUE,
        'not null' => TRUE,
        'default' => 0,
        'description' => 'UNIX timestamp of the last time this row was imported',
        'size' => 'big',
      ];
      $connection->schema()->changeField($table, 'last_imported', 'last_imported', $new);
    }
  }
}