Switch to Go 1.20 for official builds

[mx-psi]

Go 1.20 was released recently: https://go.dev/doc/go1.20

After we add testing for it on core (open-telemetry/opentelemetry-collector/issues/7159) and contrib (open-telemetry/opentelemetry-collector-contrib/issues/18454) we can switch to using the Go 1.20 compiler for official builds. Based on historical precedent this will make our life easier when dealing with security issues since we don't depend on the Go team backporting fixes and can react more quickly.

[jpkrohling]

This might even make our lives easier during the release, as we seem to have dependencies requiring 1.20 already (cc @codeboten)

[mx-psi]

I think all components on contrib should still support building with Go 1.19 per our compatibility rules, so I don't think this is a solution to that problem (although I am not aware of the specific problem). One option is to provide functionality (the one that uses those dependencies) conditionally only when building with a Go 1.20+ compiler (via the go1.20 build tag)

[mx-psi]

This is now unblocked