Upgrade to Go v1.18

[alpe]

Tracking issue
Cosmos-SDK main branch is already upgraded to use Go 1.18

Generics ...
These new language changes required a large amount of new code that has not had significant testing in production settings. That will only happen as more people write and use generic code. We believe that this feature is well implemented and high quality. However, unlike most aspects of Go, we can't back up that belief with real world experience. Therefore, while we encourage the use of generics where it makes sense, please use appropriate caution when deploying generic code in production.

[alpe]

Done in #866