PHP 8.4 Deprecations

[crynobone]

We are working on making laravel/passport PHP 8.4 compatible and saw this error

10) /home/runner/work/passport/passport/vendor/firebase/php-jwt/src/JWT.php:96
Firebase\JWT\JWT::decode(): Implicitly marking parameter $headers as nullable is deprecated, the explicit nullable type must be used instead

Triggered by:

* Laravel\Passport\Tests\Unit\ApiTokenCookieFactoryTest::test_cookie_can_be_successfully_created
  /home/runner/work/passport/passport/tests/Unit/ApiTokenCookieFactoryTest.php:21

[Slamdunk]

Already fixed in firebase/php-jwt#572