Use go 1.18

[mortent]

This updates kpt and porch to use go 1.18.

[mortent]

We'll hold off a little bit here since it impacts any downstream consumers of kpt.

[natasha41575]

qq, do we plan to switch to go workspace mode as well?

[mengqiy]

I needs golang 1.18+ in https://github.com/GoogleContainerTools/kpt/pull/3450.

# github.com/prep/wasmexec
Error: ../../../go/pkg/mod/github.com/prep/[email protected]/js.go:12:34: undefined: any
Error: ../../../go/pkg/mod/github.com/prep/[email protected]/js.go:40:19: undefined: any
Error: ../../../go/pkg/mod/github.com/prep/[email protected]/js.go:44:35: undefined: any
Error: ../../../go/pkg/mod/github.com/prep/[email protected]/js.go:55:30: undefined: any
Error: ../../../go/pkg/mod/github.com/prep/[email protected]/js.go:64:13: undefined: any
Error: ../../../go/pkg/mod/github.com/prep/[email protected]/module.go:34:33: undefined: any
Error: ../../../go/pkg/mod/github.com/prep/[email protected]/module.go:39:33: undefined: any
Error: ../../../go/pkg/mod/github.com/prep/[email protected]/module.go:70:16: undefined: any
Error: ../../../go/pkg/mod/github.com/prep/[email protected]/module.go:71:23: undefined: any
Error: ../../../go/pkg/mod/github.com/prep/[email protected]/module.go:425:46: undefined: any
Error: ../../../go/pkg/mod/github.com/prep/[email protected]/module.go:425:46: too many errors
note: module requires Go 1.18

Any ETA on this PR?

[mortent]

Updated the PR to switch to 1.18 instead of 1.19. Got feedback that forcing downstream consumers to switch to the absolute latest version could be problematic. As far as I know we don't have a strong reason to prefer 1.19 over 1.18.

@droot @mengqiy

@natasha41575 We can use go workspaces, but we need to figure out how to be use it. Not sure if it will work well to check the workspace file into git.