fix agents sdk version

Author: lusu-msft

sdk/agentserver/azure-ai-agentserver-core/pyproject.toml

@@ -21,7 +21,7 @@ keywords = ["azure", "azure sdk"]
 dependencies = [
     "azure-monitor-opentelemetry>=1.5.0",
     "azure-ai-projects==1.1.0b4",
-    "azure-ai-agents==1.2.0b6",
+    "azure-ai-agents==1.2.0b5",
     "azure-core>=1.35.0",
     "azure-identity",
     "openai>=1.80.0",