build(deps): update ttrpc requirement from 0.7 to 0.8

Updates the requirements on [ttrpc](https://github.com/containerd/ttrpc-rust) to permit the latest version.
- [Commits](containerd/ttrpc-rust@v0.7.0...v0.8.1)

---
updated-dependencies:
- dependency-name: ttrpc
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

crates/shim-protos/Cargo.toml

@@ -13,7 +13,7 @@ homepage.workspace = true
 
 [dependencies]
 protobuf = "3.1"
-ttrpc = "0.7"
+ttrpc = "0.8"
 async-trait = { version = "0.1.48", optional = true }
 
 [build-dependencies]