Fix unhandled buildvar type error

- Fix unhandled buildvar type error when using HCL syntax
- Upgrade golang version to 1.20

Author: Justin Zhang

builder/ucloud/uhost/step_create_instance.go

@@ -93,7 +93,7 @@ func (s *stepCreateInstance) Run(ctx context.Context, state multistep.StateBag)
 	state.Put("instance", instance)
 	// instance_id is the generic term used so that users can have access to the
 	// instance id inside of the provisioners, used in step_provision.
-	state.Put("instance_id", instance)
+	state.Put("instance_id", instanceId)
 
 	if instance.BootDiskState != ucloudcommon.BootDiskStateNormal {
 		ui.Say("Waiting for boot disk of instance initialized")

go.mod

@@ -1,6 +1,6 @@
 module github.com/ucloud/packer-plugin-ucloud
 
-go 1.18
+go 1.20
 
 require (
 	github.com/hashicorp/hcl/v2 v2.16.2