Add protobuf package to CI.

.github/workflows/rust.yml

@@ -17,7 +17,7 @@ jobs:
     - uses: dtolnay/rust-toolchain@1.69.0
     - uses: actions/checkout@v3
     - name: Preparing
-      run: sudo apt update && sudo apt install -y libxen-dev
+      run: sudo apt update && sudo apt install -y libxen-dev protobuf-compiler
     - name: Build
       run: cargo build --verbose
     - name: Run tests