Serialize relations when caching

Shouldn't serialization of the cache key include relations if they exist? If running various Jobs in the background, it appears the same key is used:

```
$user = $this->user->with(['groups.projects'])->find(1);
```

key = App\Repositories\UserRepository@find-fdc17b908030a12f6cbc123416fb82e5

```
$user = $this->user->with(['profile'])->find(1);
```

key = App\Repositories\UserRepository@find-fdc17b908030a12f6cbc123416fb82e5