ci: install poetry to nightly workflow

Author: Laure-di

scaleway/scaleway/instance/v1/tests/test_instance_sdk.py

@@ -122,7 +122,7 @@ def test_list_server(
 ) -> None:
     instance_api, _ = instance_block_api
     servers = instance_api.list_servers(zone=zone)
-    assert len(servers.servers) == 0
+    assert len(servers.servers) >= 1
     assert servers.servers[0].name == server_name