Fix test-generator feature dependency

[mikkelhegn]

Using componentize-py as a dependency from another project (following these instructions: #160), it fails to build with the following error:

Compiling componentize-py-shared v0.1.0 (/Users/mikkel/code/fermyon/componentize-py/shared)
error[E0277]: the trait bound `getrandom::Error: std::error::Error` is not satisfied
   --> /Users/mikkel/code/fermyon/componentize-py/test-generator/src/lib.rs:549:40
    |
549 |         getrandom::getrandom(&mut seed)?;
    |                                        ^ the trait `std::error::Error` is not implemented for `getrandom::Error`
    |
    = help: the trait `FromResidual<Result<Infallible, E>>` is implemented for `Result<T, F>`
    = note: required for `anyhow::Error` to implement `From<getrandom::Error>`
    = note: required for `Result<(), anyhow::Error>` to implement `FromResidual<Result<Infallible, getrandom::Error>>

Consulting with @alexcrichton (thank you) I got the following:

This has to do with version/feature resolution in Rust where componentize-py has a Cargo.lock which uses one set of dependencies/versions but when you build externally you don't start with that so by default you pull in newer versions of dependencies. This uncovers a preexisting bug in componentize-py where it's accidentally relying on a crate feature being enabled for a crate without explicitly enabling it. That happens to work within componentize-py because some other crate enables the feature (somehow, transitively, etc) but doesn't work externally because nothing else enables it.

The "true fix" is to change test-generator's dependency on getrandom to getrandom = { version = "0.2.15", features = ['std'] }. A "workaround fix" would be to add that dependency directive to your own Cargo.toml

I've validated the below fix in my instance of referencing componentize-py from another project.

[dicej]

Thanks!