deps: upgrading to ibc-go/v6-alpha1

[damiannolan]

Description

This PR upgrades the ibc-go dependency to v6.0.0-alpha1.
This allows ibc-go/e2e to point to a compatible ibctest version and facilitates running e2e tests for the upcoming v6 release.

For example:

• e2e: ICS27 interchain accounts x/group integration cosmos/ibc-go#2195

This PR targets main but happy to also get this upstreamed to a upgrades/ibc-go/v6-alpha1 branch if that would minimise disruption to dev workflow.

Everything on this branch seems to compile fine with the upgrade to v6.0.0-alpha1, however running make ibctest from the root of the repo fails with:

go generate ./...
go test -ldflags "-X github.com/strangelove-ventures/ibctest/v5/internal/version.GitSha=628dd20" -c -o ./bin/ibctest ./cmd/ibctest
main module (github.com/strangelove-ventures/ibctest/v5) does not contain package github.com/strangelove-ventures/ibctest/v5/cmd/ibctest
make: *** [ibctest] Error 1

This also seems to be the case on main.

Let me know if there's anything else required to get this merged. Cheers!

[DavidNix]

For transparency, Strangelove created a v5 branch of upstream right before this merge. We'll keep main in lockstep with ibc-go.

As fas we know, no one needs ibc-go/v5. So we will allow that branch to go stale unless the community deems otherwise.

We have a v3 branch that's kept up to date for team's still on ibc-go/v3.