mypy no longer likes gel_client.get() and .query()

This code:

```python
user = await gel_client.get(default.User, None)
```

causes these typing errors:

```bash
app/api/router.py:48: error: Function does not return a value (it only ever returns None) [func-returns-value]
app/api/router.py:48: error: Argument 1 to "get" of "AsyncIOReadOnlyExecutor" has incompatible type "type[User]"; expected "QueryableObject[None] | type[QueryableType[None]]" [arg-type]
```

on the latest `master` (`688968c948a7610396669c93cab98ea635081554`)