How should I use `notEmpty`?

[hirasso]

Hi there! I'd love to have a way to do this:

$dotenv->notEmpty(['MY_FIRST_VAR', 'MY_SECOND_VAR']);

...with the same behavior as $dotenv->required.

The function is already there, but there doesn't seem to be a public API:

phpdotenv/src/Validator.php

Lines 68 to 76 in a59a137

	public function notEmpty()
	{
	return $this->assertNullable(
	static function (string $value) {
	return Str::len(\trim($value)) > 0;
	},
	'is empty'
	);
	}

I'd submit a PR if you accept one :)