feat: upgrade to v4 (backport #357)

[mergify]

Description

This PR upgrades the app version to v4-Marigold.

Checklist:

• I followed the contributing guidelines and code of conduct.
• I have added a relevant changelog to CHANGELOG.md
• I have added tests to cover my changes.
• I have updated the documentation accordingly.

---

This is an automatic backport of pull request #357 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of d239ccf has failed:

On branch mergify/bp/release/v4.0.x/pr-357
Your branch is up to date with 'origin/release/v4.0.x'.

You are currently cherry-picking commit d239ccf.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   .github/workflows/check-generated.yml
	modified:   ante/ante_test.go
	modified:   app/app.go
	modified:   app/encoding.go
	modified:   app/helpers/test_helpers.go
	modified:   cli_test/cli_test.go
	modified:   cli_test/multi_test.go
	modified:   cli_test/test_helpers.go
	modified:   cmd/fnsad/cmd/root.go
	modified:   cmd/fnsad/cmd/testnet_test.go
	modified:   cmd/fnsad/main.go
	modified:   go.mod
	modified:   interchaintest/go.mod

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   CHANGELOG.md

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

❗ No coverage uploaded for pull request base (release/v4.0.x@8fd1268). Click here to learn what that means.

Additional details and impacted files

@@                Coverage Diff                @@
##             release/v4.0.x     #358   +/-   ##
=================================================
  Coverage                  ?   50.31%           
=================================================
  Files                     ?       10           
  Lines                     ?     1407           
  Branches                  ?        0           
=================================================
  Hits                      ?      708           
  Misses                    ?      654           
  Partials                  ?       45           

Files	Coverage Δ
app/app.go	83.87% <ø> (ø)
app/encoding.go	100.00% <ø> (ø)
cmd/fnsad/cmd/root.go	11.87% <ø> (ø)