chore(deps): bump github.com/stackitcloud/stackit-sdk-go/services/observability from 0.15.1 to 0.16.1

chore(deps): bump github.com/stackitcloud/stackit-sdk-go/services/observability from 0.15.1 to 0.16.1 #3930