Fix typing for factory

Since repositories extend a base class, they can have method
that are not in this base class.

The issue with using `Repository<T>` as the return type is
that PHPStan cannot see those methods.

For example: https://phpstan.org/r/65389bf5-b00d-4e5d-b993-8c6f274b7545

With this change, PHPStan understands the correct class while still
forcing classes to extend `Repository`.

For example: https://phpstan.org/r/d40317b1-1834-407b-9284-ca1e7b0d3325

src/Ting/Repository/RepositoryFactory.php

@@ -102,9 +102,10 @@ public function __construct(
     }
 
     /**
-     * @param class-string<Repository<T>> $repositoryName
-     * @return Repository<T>
+     * @param class-string<R> $repositoryName
+     * @return R
      * @template T of object
+     * @template R of Repository<T>
      */
     public function get($repositoryName)
     {