chore: release 0.9.0 (#161)

* chore: release 0.9.0

* update samples to reflect changes in the code

Co-authored-by: release-please[bot] <55107282+release-please[bot]@users.noreply.github.com>
Co-authored-by: Anthonios Partheniou <partheniou@google.com>

compute/compute/snippets/sample_start_stop.py

@@ -43,7 +43,7 @@ def start_instance(project_id: str, zone: str, instance_name: str):
     instance_client = compute_v1.InstancesClient()
     op_client = compute_v1.ZoneOperationsClient()
 
-    op = instance_client.start(project=project_id, zone=zone, instance=instance_name)
+    op = instance_client.start_unary(project=project_id, zone=zone, instance=instance_name)
 
     while op.status != compute_v1.Operation.Status.DONE:
         op = op_client.wait(operation=op.name, zone=zone, project=project_id)