dataProvider & Tester\DataProvider::testQuery() must be of the type string

Version: 2.3.2

Documentation mentions, that `data-provider.php` can return numerically indexed array, but after adding scalar typehints, `testQuery()` failes.

```
TypeError: Argument 1 passed to Tester\DataProvider::testQuery() must be of the type string, int given, called in .../nette/tester/src/Framework/DataProvider.php on line 46
```
