[Dependencies] bump cosmos-sdk client lib

[okdas]

Summary

Bumps cosmossdk.io/client/v2 to v2.0.0-beta.8.

Issue

• Issue: [Cosmos] Revisit the encoding limitation of the newer version of cosmos #1033

Type of change

Select one or more from the following:

• New feature, functionality or library
• Consensus breaking; add the consensus-breaking label if so. See [Infra] Automatically add the consensus-breaking label #791 for details
• Bug fix
• Code health or cleanup
• Documentation
• Other (specify)

Sanity Checklist

• I have updated the GitHub Issue assignees, reviewers, labels, project, iteration and milestone
• For docs, I have run make docusaurus_start
• For code, I have run make go_develop_and_test and make test_e2e
• For code, I have added the devnet-test-e2e label to run E2E tests in CI
• For configurations, I have update the documentation
• I added TODOs where applicable

[okdas]

I'm hitting the same mockgen issue I've encountered in #865. Want to check if there's the same issue on CI.

[Olshansk]

@okdas Upgrading to the next cosmos version will be important VERY soon.

Tending to this now would not be wasted effort.