[10.x] Do not use null to initialise $lastExecutionStartedAt (#46285)

* Initialise $lastExecutionStartedAt with Carbon::now()

$lastExecutionStartedAt is passed to Carbon::equalTo(). Passing a null value to this method will result in deprecation message.

* Update ScheduleWorkCommand.php

---------

Co-authored-by: Taylor Otwell <[email protected]>

Author: TimmayNL

src/Illuminate/Console/Scheduling/ScheduleWorkCommand.php

@@ -38,7 +38,7 @@ public function handle()
             $this->getLaravel()->isLocal() ? OutputInterface::VERBOSITY_NORMAL : OutputInterface::VERBOSITY_VERBOSE
         );
 
-        [$lastExecutionStartedAt, $executions] = [null, []];
+        [$lastExecutionStartedAt, $executions] = [Carbon::now()->subMinutes(10), []];
 
         $command = implode(' ', array_map(fn ($arg) => ProcessUtils::escapeArgument($arg), [
             PHP_BINARY,