Update tendermint-proto requirement from 0.30 to 0.31 (#88)

Updates the requirements on [tendermint-proto](https://github.com/informalsystems/tendermint-rs) to permit the latest version.
- [Release notes](https://github.com/informalsystems/tendermint-rs/releases)
- [Changelog](https://github.com/informalsystems/tendermint-rs/blob/main/CHANGELOG.md)
- [Commits](informalsystems/tendermint-rs@v0.30.0...v0.31.1)

---
updated-dependencies:
- dependency-name: tendermint-proto
  dependency-type: direct:production
...

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

Cargo.toml

@@ -45,7 +45,7 @@ scale-info         = { version = "2.1.2", default-features = false, features = [
 borsh = { version = "0.10.0", default-features = false, optional = true }
 
 [dependencies.tendermint-proto]
-version          = "0.30"
+version          = "0.31"
 default-features = false
 
 [features]