fix: Data lakehouse demo flow file (25.3) (#335)

download NiFi flow from 25.3 release branch

Author: labrenbe

demos/data-lakehouse-iceberg-trino-spark/create-nifi-ingestion-job.yaml

@@ -67,7 +67,7 @@ data:
     service_login(username=USERNAME, password=PASSWORD)
     print("Logged in")
 
-    response = requests.get("https://raw.githubusercontent.com/stackabletech/demos/refs/heads/main/demos/data-lakehouse-iceberg-trino-spark/LakehouseKafkaIngest.json")
+    response = requests.get("https://raw.githubusercontent.com/stackabletech/demos/refs/heads/release-25.3/demos/data-lakehouse-iceberg-trino-spark/LakehouseKafkaIngest.json")
 
     filename = "/tmp/LakehouseKafkaIngest.json"
     with open(filename, "wb") as f: