Fix RequiredRuleInferrerTest using non-existent enum class

The test used `new Enum('SomeClass')` but recent Laravel versions call
`::cases()` in `Enum::__toString()`, causing a class not found error.
Replace with `DummyBackedEnum::class` which is a real enum.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: rubenvanassche

tests/RuleInferrers/RequiredRuleInferrerTest.php

@@ -17,6 +17,7 @@
 use Spatie\LaravelData\Support\Validation\ValidationContext;
 use Spatie\LaravelData\Support\Validation\ValidationPath;
 use Spatie\LaravelData\Tests\Factories\FakeDataStructureFactory;
+use Spatie\LaravelData\Tests\Fakes\Enums\DummyBackedEnum;
 use Spatie\LaravelData\Tests\Fakes\SimpleData;
 
 /**
@@ -126,13 +127,13 @@ function () {
     $rules = $this->inferrer->handle(
         $dataProperty,
         PropertyRules::create()->add(
-            new \Spatie\LaravelData\Attributes\Validation\Enum(new BaseEnum('SomeClass'))
+            new \Spatie\LaravelData\Attributes\Validation\Enum(new BaseEnum(DummyBackedEnum::class))
         ),
         new ValidationContext([], [], ValidationPath::create(null))
     );
 
     expect(app(RuleDenormalizer::class)->execute($rules->all(), ValidationPath::create()))->toEqualCanonicalizing([
-        'required', new BaseEnum('SomeClass'),
+        'required', new BaseEnum(DummyBackedEnum::class),
     ]);
 });