Update to multi-package publishing w/ new Cargo release (0.90?)

[rvagg]

This will probably be in the next Cargo release: rust-lang/cargo#15636 - includes --workspace publishing plus --dry-run, which is something we've wanted to get closer to auto-publishing.

See in particular this: #2027 (comment) & this #2027 (comment) ("the lack of a a viable cargo publish --workspace --dry-run makes all this really hard")—no longer! So we can hopefully reopen that PR and proceed.

Same with builtin-actors and actors-utils.

Related:

• CI: Publish dry-run #2004
• Create updated release process #2018
• Releases are triggered by code review #2025

h/t to Steb for pointing this one out.

[rvagg]

Also potentially relevant is trusted publishing with crates.io: https://blog.rust-lang.org/2025/07/11/crates-io-development-update-2025-07/

[BigLep]

It looks like rust-lang/cargo#15636 is in for cargo 1.90 which looks to be set for release 2025-09-18 per https://doc.rust-lang.org/nightly/cargo/CHANGELOG.html#cargo-190-2025-09-18