Update Dockerfile

Dockerfile

@@ -22,7 +22,4 @@ echo "This is the MCP server for LeChat integration"\n\
 echo "MCP Tools: create_room, make_move, send_chat, get_room_state, list_rooms"\n\
 python mcp_server.py' > start.sh && chmod +x start.sh
 
-# Set required environment variable for Mistral API
-ENV MISTRAL_API_KEY=""
-
 CMD ["./start.sh"]