when creating an ICD crate with just postcard-rpc as a dependency it will fail to compile when you e.g. use the endpoints! macro with

error[E0433]: failed to resolve: use of unresolved module or unlinked crate postcard_schema

IMHO the postcard-rpc macro shouldn't rely on the consumer to also pull in postcard-schema as a dependency (which they aren't even using). instead it could/should pull it in as a dependency itself and pub use it and then reference that. this way it'd also be ensured that the code generated by the postcard-rpc macro is using a version of postcard-schema with which it is compatible.