Compilation error with rust 1.40

[ln42]

Hey there, thanks for the awesome work on lv2 support with Rust!

I just got back on a project I left a couple weeks and it's not compiling anymore:

error[E0432]: unresolved import `proc_macro`
 --> /.cargo/registry/src/github.heygears.com-1ecc6299db9ec823/urid-derive-0.1.0/src/lib.rs:7:5
  |
7 | use proc_macro::TokenStream;
  |     ^^^^^^^^^^ help: a similar path exists: `syn::proc_macro`

error[E0432]: unresolved import `proc_macro`
 --> /.cargo/registry/src/github.heygears.com-1ecc6299db9ec823/urid-derive-0.1.0/src/uri_bound.rs:2:5
  |
2 | use proc_macro::TokenStream;
  |     ^^^^^^^^^^ help: a similar path exists: `syn::proc_macro`

error[E0432]: unresolved import `proc_macro`
 --> /.cargo/registry/src/github.heygears.com-1ecc6299db9ec823/urid-derive-0.1.0/src/urid_collection_derive.rs:1:5
  |
1 | use proc_macro::TokenStream;
  |     ^^^^^^^^^^ help: a similar path exists: `syn::proc_macro`

error: aborting due to 3 previous errors

I'll try to fix it myself by cloning the repo locally, but I thought it was worth reporting as I tried with latest develop and had the same error.

Cheers

[ln42]

Fixed with #83

[JOOpdenhoevel]

I can reproduce this error. This problem was fixed back in March with 1.42.0, but I will merge the fix nonetheless. However, I would kindly ask you to update your toolchain! 😅 We haven't made it official, but in practice we are only targeting the currently stable versions of Rust, which is 1.46.0 as of this writing.