Changed 'stock' column type from decimal to unsigned medium integer

[yoeriboven]

Fixes #9

[fulopattila122]

Thanks for the PR.

• Stock can be decimal because one can have non-integer units as well, eg 1.7L which is being sold in 0.1 or 0.2, etc units.

On the other hand we never change existing migrations, but would add a new one to change an existing column. It is a breaking change thus it would also require a bump of a major version.

You can add this migration to your project that you're building on top of this module and convert the field to integer locally. As you see it's highly unlikely that this field will be changed later in the framework.

We've created the modules/framework in a way that you can easily customize it. Thus we accept PRs that are serving the generic nature and not the specifics, like this one.