forceNew on issuer (#6245) (#12073)

Co-authored-by: Edward Sun <[email protected]>
Signed-off-by: Modular Magician <[email protected]>

Co-authored-by: Edward Sun <[email protected]>

Author: modular-magician

.changelog/6245.txt

@@ -0,0 +1,3 @@
+```release-note:bug
+gkehub: fixed `issuer` can't be updated on `google_gke_hub_membership`
+```

google/resource_gke_hub_membership.go

@@ -70,6 +70,7 @@ https://cloud.google.com/kubernetes-engine/docs/how-to/workload-identity`,
 						"issuer": {
 							Type:     schema.TypeString,
 							Required: true,
+							ForceNew: true,
 							Description: `A JSON Web Token (JWT) issuer URI. 'issuer' must start with 'https://' and // be a valid 
 with length <2000 characters. For example: 'https://container.googleapis.com/v1/projects/my-project/locations/us-west1/clusters/my-cluster' (must be 'locations' rather than 'zones'). If the cluster is provisioned with Terraform, this is '"https://container.googleapis.com/v1/${google_container_cluster.my-cluster.id}"'.`,
 						},