make __nutype_{type_name}__ compatible with clippy lint

[vic1707]

rust analyzer in VSCode complains about generated nutype module not being proper snake case, this PR fixes that with a naive to_lower_case call as I think nobody really cares about how exactly it is named except clippy x).

[greyblake]

Thanks.
I think we should rather ignore the lint explicitly.

My concern is having 2 different types like

struct Notebook(..)

struct NotEBook(..)

can cause undesired collision in the module names.

[greyblake]

@vic1707 Could you please apply #[allow(non_snake_case)] instead?

[vic1707]

Yeah you're right, I didn't think about it 👍
I chose to #[allow(non_snake_case, reason = "we keep original structure name which is probably CamelCase")].
Since not providing a reason can also trigger a warning x)

(yes I pretty much enable every available lint on my projects, sometimes a pain but worth it since I learn a lot and helpful when clippy suggests better versions of my code)

[greyblake]

Thank you!