don't let CARTA url overwrite metadata

shared/workspaces/workspaces/capability/services/capability_service.py

@@ -246,7 +246,11 @@ class CapabilityService(CapabilityServiceIF):
 
         execution = self.capability_info.lookup_execution_by_workflow_request_id(parent_wf_request_id)
         request_version = execution.version
-        request_version.workflow_metadata = {"carta_url": message["carta_url"]}
+        workflow_info = request_version.workflow_metadata
+        if workflow_info:
+            request_version.workflow_metadata = {**workflow_info, "carta_url": message["carta_url"]}
+        else:
+            request_version.workflow_metadata = {"carta_url": message["carta_url"]}
 
         self.capability_info.save_entity(request_version)