Tests are only run on workspace default package

See the [test project here](https://gitlab.com/detly/bacon-workspace-test). It's a simple workspace project with a member package `member-one`. The `member-one` package has an error in a unit test, so it builds when `cargo build --workspace` or `cargo test` are run from the root, but fails when `cargo test --workspace` is run from the root.

If I run `bacon` in the root directory, it builds the whole workspace by default. If you create an error in `member-one` in the non-test code, it's shown. If you remove it, it all passes.

If I then press t, Bacon still shows the project as passing, even though using `cargo test --workspace` directly fails. It seems like Bacon is doing a whole-workspace build, but not testing the whole workspace.

Versions:
- bacon: 2.16.0
- rustc: 1.77.0
- cargo: 1.77.0
- OS: Ubuntu 23.10

Rust toolchain installed via Rustup, default is stable. Bacon installed via Cargo.

Reproduce the behavior with the linked workspace project, comparing Bacon's build and t-key test actions with cargo test --workspace from the root. Trace the command path used for the t action and verify that member-one's failing unit test is included; done means Bacon reports the workspace test failure consistently with Cargo.

Written by the indexing model from the issue text.