Support migrate_tools RC versions.

composer.json

@@ -11,7 +11,7 @@
     "name": "drupal/reinstall",
     "require": {
         "drupal/migrate_plus": "^2.0",
-        "drupal/migrate_tools": "^3.0"
+        "drupal/migrate_tools": "^3.0@RC"
     },
     "type": "drupal-module"
 }