Update the protobuf dependency

[jorgeantonio21]

I have realized that raft-rs relies on a very old version of protobuf, which has a series of dependencies vulnerabilities (found by running cargo deny). It would be great to update the protobuf dependency to the latest.

[ti-chi-bot]

Welcome @jorgeantonio21! It looks like this is your first issue to tikv/raft-rs 🎉

[jorgeantonio21]

To be more precise, here is the output of running cargo audit:

% cargo audit
    Fetching advisory database from `https://github.com/RustSec/advisory-db.git`
      Loaded 821 security advisories (from /Users/jorgeantonio/.cargo/advisory-db)
    Updating crates.io index
    Scanning Cargo.lock for vulnerabilities (464 crate dependencies)
Crate:     protobuf
Version:   2.28.0
Title:     Crash due to uncontrolled recursion in protobuf crate
Date:      2024-12-12
ID:        RUSTSEC-2024-0437
URL:       https://rustsec.org/advisories/RUSTSEC-2024-0437
Solution:  Upgrade to >=3.7.2
Dependency tree:
protobuf 2.28.0
├── zippy 0.1.0
├── raft-proto 0.7.0
│   └── raft 0.7.0
│       └── zippy 0.1.0
└── raft 0.7.0

Crate:     fxhash
Version:   0.2.1
Warning:   unmaintained
Title:     fxhash - no longer maintained
Date:      2025-09-05
ID:        RUSTSEC-2025-0057
URL:       https://rustsec.org/advisories/RUSTSEC-2025-0057
Dependency tree:
fxhash 0.2.1
├── tracing-timing 0.7.0
│   └── zippy 0.1.0
└── raft 0.7.0
    └── zippy 0.1.0

error: 1 vulnerability found!
warning: 1 allowed warning found

[glorv]

@jorgeantonio21 Because protobuf 3.x is not compatible with 2.x, upgrading to 3.x is a breaking change. So we don't have a plan to migrate to v3.x. Maybe you can submit an issue in the repo rust-protobuf to ask a fix for v2.x.

[jorgeantonio21]

I have requested this on the rust-protobuf repository:

stepancheg/rust-protobuf#773

Just ofc, could there be some added value to updated protobuf ? Even though this is a breaking change, could be worth pursuing it ?