modules/apps/callbacks/v0.2.0+ibc-go-v8.0

This release bumps ibc-go to v8.0.0 and introduces two fixes:

• The event that is emitted when the callback cannot be executed due to a panic or an out of gas error indicates now that an error occurred.

• The packet is not be sent unless the `IBCSendPacketCallback` returns `nil` explicitly (see this issue for more information).

Please also note that this release requires a coordinated upgrade.