Binding BLOB requires narrowing conversion

```
const int lengthInBytes =
      static_cast<int>(sizeof(uint8_t) * binary->raw().size());
insert.bind(1, binary->raw().data(), lengthInBytes);
```

Would be nice if the API took size_t or something so that I don't have to narrow it.
On my machine size_type (size_t) is unsigned long.