Github sync is trying to sync events for repos that are connected to projects

# Problem

```
** (ArgumentError) nil given for :project_id. Comparison with nil is forbidden as it is unsafe. Instead write a query with is_nil/1, for example: is_nil(s.project_id)
```

This error is happening as the webhook handler is trying to sync data for repos that do not have a corresponding `project_id`.

We should ignore the event since there is no project to actually sync to.