chore: update informalsystems-pbjson-build requirement in /rust

Updates the requirements on [informalsystems-pbjson-build](https://github.com/informalsystems/pbjson) to permit the latest version.
- [Release notes](https://github.com/informalsystems/pbjson/releases)
- [Changelog](https://github.com/informalsystems/pbjson/blob/main/CHANGELOG.md)
- [Commits](informalsystems/pbjson@v0.6.0...v0.7.0)

---
updated-dependencies:
- dependency-name: informalsystems-pbjson-build
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

rust/codegen/Cargo.toml

@@ -10,4 +10,4 @@ edition = "2018"
 bytes = "1.0.1"
 prost = "0.12"
 prost-build = "0.12"
-informalsystems-pbjson-build = "0.6.0"
+informalsystems-pbjson-build = "0.7.0"