[8.x] Use Fluent instead of array on Rule::when()

[crynobone]

Consistent with Illuminate\Validation\Validator::sometimes()

framework/src/Illuminate/Validation/Validator.php

Lines 1115 to 1126 in 59b674a

	public function sometimes($attribute, $rules, callable $callback)
	{
	$payload = new Fluent($this->getData());
	if ($callback($payload)) {
	foreach ((array) $attribute as $key) {
	$this->addRules([$key => $rules]);
	}
	}
	return $this;
	}

Signed-off-by: Mior Muhammad Zaki crynobone@gmail.com

[driesvints]

Hi, I merged #38398 into 8.x to get the test suite passing again. I've put your PR in draft. Please rebase your PR against 8.x to make the tests of this PR pass. After you've done that and tests pass, mark this PR as ready for review. Thanks.

[crynobone]

Done @driesvints