Bump prost from 0.7.0 to 0.8.0 (#9560)

Bumps [prost](https://github.com/tokio-rs/prost) from 0.7.0 to 0.8.0.
- [Release notes](https://github.com/tokio-rs/prost/releases)
- [Commits](https://github.com/tokio-rs/prost/compare/v0.7.0...v0.8.0)

---
updated-dependencies:
- dependency-name: prost
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

substrate/client/network/Cargo.toml

@@ -41,7 +41,7 @@ log = "0.4.8"
 parking_lot = "0.11.1"
 pin-project = "1.0.4"
 prometheus-endpoint = { package = "substrate-prometheus-endpoint", version = "0.9.0", path = "../../utils/prometheus" }
-prost = "0.7"
+prost = "0.8"
 rand = "0.7.2"
 sc-block-builder = { version = "0.10.0-dev", path = "../block-builder" }
 sc-client-api = { version = "4.0.0-dev", path = "../api" }