Bump protobufjs and @cosmjs/stargate in /solidity (#251)

Bumps [protobufjs](https://github.com/protobufjs/protobuf.js) to 6.11.4 and updates ancestor dependency [@cosmjs/stargate](https://github.com/cosmos/cosmjs). These dependencies need to be updated together.


Updates `protobufjs` from 6.10.3 to 6.11.4
- [Release notes](https://github.com/protobufjs/protobuf.js/releases)
- [Changelog](https://github.com/protobufjs/protobuf.js/blob/master/CHANGELOG.md)
- [Commits](https://github.com/protobufjs/protobuf.js/commits)

Updates `@cosmjs/stargate` from 0.25.6 to 0.31.0
- [Changelog](https://github.com/cosmos/cosmjs/blob/main/CHANGELOG.md)
- [Commits](cosmos/cosmjs@v0.25.6...v0.31.0)

---
updated-dependencies:
- dependency-name: protobufjs
  dependency-type: indirect
- dependency-name: "@cosmjs/stargate"
  dependency-type: direct:production
...

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