Fix `count` method return value. #4.0

Hi there, I have very simple query
```php
dd($this->borrowings()->count());
```

**Actual output**
```
string(1) "1"
```

**Expected output**
```
int(1)
```

Happens on 4.1.x, but probably on 4.x versions as well.  
Since this, we cannot relly on `===` comparsion operator, which result into `false` all the time.  
Is this behaviour by design, or just a flaw?