Aggregate does not allow to get a float (decimal) value

Aggregate API returns an integer, how do I aggregate a float field?

For instance, I have a decimal price field in my database and I would like to find a sum of all prices:

```go
total, err := repo.Aggregate(ctx, rel.From("products"), "SUM", "price")
```

Instead of getting a sum I'm getting an error

```
sql: Scan error on column index 0, name "result": converting driver.Value type []uint8 ("1.00000000") to a int64: invalid syntax
```

Field price has type `DECIMAL` in MySQL database.