fix: add qwen to no-temperature models in document labeler

The document labeler was sending temperature=0.1 for Qwen models, while
agent.rs already excluded qwen from temperature. Align both to use
temperature=None for qwen to match the model's recommended settings.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: brainless

dwata-agents/src/kg_email_extractor/document_labeler.rs

@@ -127,7 +127,10 @@ impl TemplateDocumentLabelerAgent {
                 max_tokens: 512,
                 model: self.model.clone(),
                 system: Some(system_prompt.clone()),
-                temperature: if self.model.contains("nano") || self.model.contains("mini") {
+                temperature: if self.model.contains("nano")
+                    || self.model.contains("mini")
+                    || self.model.contains("qwen")
+                {
                     None
                 } else {
                     Some(0.1)