Commit b608a788 (cli: `rad config schema` emits JSON Schema, 2025-04-28)
added a feature flag that enables the "schemars" optional dependency.
Crate radicle-node doesn't use this feature.
Crate radicle fails to compile when the feature is disabled.
This is reproducible with "flake check".
Fix it.
Note that a "cargo build" of the entire workspace doesn't fail, because the
feature is enabled due to "unification", since "radicle-cli" does use this
feature. From https://doc.rust-lang.org/cargo/reference/resolver.html#features:
> When building multiple packages in a workspace (such as with --workspace
> or multiple -p flags), the features [of the dependencies] of all of those
> packages are unified. If you have a circumstance where you want to avoid
> that unification for different workspace members, you will need to build
> them via separate cargo invocations.