Allow checks to be serializable

[Riley19280]

Currently, trying to use a conditional such as ->if or ->unless on a QueueCheck does not work, and throws an error when calling DispatchQueueCheckJobsCommand. The error message is Serialization of 'Closure' is not allowed, because it can't serialize the run checks. For example, the following check would throw this error because of the closure.

QueueCheck::new()->if(fn() => true),

This PR allows all checks to be serializable and correctly pushed to queues

[freekmurze]

Thank you!

[sebastiaanluca]

We just deployed this to production and got some exceptions:

  Laravel\SerializableClosure\SerializableClosure::__construct(): Argument #1 ($closure) must be of type Closure, true given, called in /vendor/spatie/laravel-health/src/Checks/Check.php on line 133

For

Schedule::command(DispatchQueueCheckJobsCommand::class)
    ->everyMinute()
    ->environments(['staging', 'production']);

$shouldRun is true which it can't serialize.

Line:

$serializableClosures[] = new SerializableClosure($shouldRun);

Data:

array:8 [
  "expression" => "* * * * *"
  "name" => null
  "label" => null
  "shouldRun" => array:1 [
    0 => true
  ]
  "cacheKey" => "health:checks:queue:latestHeartbeatAt"
  "cacheStoreName" => null
  "failWhenTestJobTakesLongerThanMinutes" => 10
  "onQueues" => array:2 [
    0 => "high"
    1 => "default"
  ]
]

[Riley19280]

Fixed in #233