Update rector.

Author: jhedstrom

composer.json

@@ -29,7 +29,7 @@
     "drush-ops/behat-drush-endpoint": "*",
     "php-parallel-lint/php-parallel-lint": "^1.0",
     "dms/phpunit-arraysubset-asserts": "^0.4.0 || ^0.5.0",
-    "palantirnet/drupal-rector": "^0.13",
+    "palantirnet/drupal-rector": "^0.20",
     "symfony/phpunit-bridge": "^6.1"
   },
   "conflict": {