build(deps): Bump @cosmjs/proto-signing from 0.31.1 to 0.31.3

Bumps [@cosmjs/proto-signing](https://github.com/cosmos/cosmjs) from 0.31.1 to 0.31.3.
- [Changelog](https://github.com/cosmos/cosmjs/blob/main/CHANGELOG.md)
- [Commits](cosmos/cosmjs@v0.31.1...v0.31.3)

---
updated-dependencies:
- dependency-name: "@cosmjs/proto-signing"
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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