cargo updater crashes on target-specific path dependency without version

[dillona]

Environment details

• OS: Linux 5.15.0-164-fips x86_64
• Node.js version: v22.17.0
• npm version: 10.9.2
• release-please version: 17.2.0

Steps to reproduce

1. Create a Rust crate Cargo.toml with a target-specific dependency that uses path but no version, for example:
   [target.'cfg(target_os = "linux")'.dependencies]
internal-metrics = { path = "../internal-metrics", features = ["heap"] }
2. Run release-please with the cargo-workspace plugin so CargoToml.updateContent attempts to update that dependency via versionsMap.
3. Observe release-please trying to update:
   target.cfg(target_os = "linux").dependencies.internal-metrics.version
4. It fails with:
   path not found in object: target.cfg(target_os = "linux").dependencies.internal-metrics.version