fix: open function is undefined

[SamuelScheit]

I've tried to use the KV Storage class from op-sqlite but got the error [TypeError: 0, _.open is not a function (it is undefined)] on android (weirdly enough it works on ios).
I've fixed the error by changing the import in Storage.ts from:

import { open, type DB } from '.';

to

import { open, type DB } from './index';

[ospfranco]

Ah, weird, thanks!