SDK: CI testing for backwards compatibility in Go versions other than most recent

[jakedoublev]

The SDK currently utilizes Go 1.21 in its go.mod and we rely on the service go module in CI as of #1407. Previously the CI pipeline was hardcoded to 1.22.5 as the Go version.

We need to ensure any SDK changes are backwards compatible with older Go versions, and this should be effectively tested in a dedicated CI job.