Fix test_project_publish. (#4894)

## Motivation

`test_project_publish` started failing because ruzstd 0.8.2 was
published and doesn't build with Rust 1.86.0. Due to
#4742, we cannot
upgrade to 1.87.0 or later at the moment.

## Proposal

Fix the ruzstd version to `=0.8.1`.

## Test Plan

CI should pass now. It fixed the test for me locally.

## Release Plan

- These changes should be backported to `testnet_conway`.

## Links

- [reviewer
checklist](https://github.com/linera-io/linera-protocol/blob/main/CONTRIBUTING.md#reviewer-checklist)

Author: afck

Cargo.toml

@@ -212,7 +212,9 @@ revm-state = { version = "4.0.1", default-features = false, features = [
     "serde",
 ] }
 rocksdb = "0.21.0"
-ruzstd = "0.8.1"
+# 0.8.2 doesn't build with Rust 1.87. Remove `=` once
+# https://github.com/linera-io/linera-protocol/issues/4742 is resolved.
+ruzstd = "=0.8.1"
 scylla = "~1.1.0"
 semver = "1.0.22"
 serde = { version = "1.0.197", features = ["derive"] }