add null check to setReport

[TonsiTT]

Prevents exception if setReport is given null as argument

[Linux123123]

I am also experiencing this issue, this PR fixes it

TypeError
Zackaj\LaravelDebounce\DebounceJob::setReport(): Argument #1 ($report) must be of type Zackaj\LaravelDebounce\Trackers\Report, null given, called in .../vendor/zackaj/laravel-debounce/src/Debouncers/JobDebouncer.php on line 26

[zackAJ]

Thanks @TonsiTT for contributing, Can you add a test for this case ?
If not let me know and I'll take a look.

[TonsiTT]

Not exactly sure on the test case. I am using on a job normally and some runs of the job give this error. I am not using any other aspect of the library apart from 'extends'

class ProductUpdateJob extends DebounceJob