Add more test for create VRF WF

test/workflows/vrf/test_create_vrf.py

 import pytest
 from orchestrator.types import SubscriptionLifecycle
+from pydantic_forms.exceptions import FormValidationError
 
 from gso.products import ProductName
 from gso.products.product_types.vrf import VRF
@@ -40,3 +41,15 @@ def test_create_vrf_success(
     assert subscription.vrf.route_target == vrf_input[1]["route_target"]
     assert subscription.vrf.vrf_as_number == vrf_input[1]["vrf_as_number"]
     assert subscription.description == f"VRF {vrf_input[1]["vrf_name"]}"
+
+
+@pytest.mark.workflow()
+def test_create_vrf_with_duplicate_vrf_name(
+    vrf_input,
+    faker,
+    vrf_subscription_factory,
+    data_config_filename,
+):
+    vrf_subscription_factory(vrf_name=vrf_input[1]["vrf_name"])
+    with pytest.raises(FormValidationError, match="VRF name must be unique."):
+        run_workflow("create_vrf", vrf_input)