fix: bump copilotkit to 0.1.83

Fixes missing import re in copilotkit_lg_middleware (CopilotKit#3491).

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

Author: tylerslaton

patterns/langgraph-single-agent/requirements.txt

@@ -3,7 +3,7 @@ fastapi==0.115.12
 uvicorn==0.34.2
 ag-ui-protocol>=0.1.10
 ag-ui-langgraph==0.0.28
-copilotkit==0.1.82
+copilotkit==0.1.83
 partialjson>=0.0.8
 langgraph==1.0.10rc1
 langchain>=0.3.0