Fix the 'Validate' Attribute. Currently the 'rule' property passed to
the Validate constructor was normalized but wrong value was checked.
Now the Validate attribute should works properly if it's initialized
with something like this:

```php
<?php

class Foo {
  public function bar(
    #[Validate('some-rule')]
    string $name
  ): string {
    return 'ok';
  }
}
```