fix: Fix the problem of multiple line breaks in Q&A (#1573)

web/components/common/completion-input.tsx

@@ -60,6 +60,7 @@ function CompletionInput({ children, loading, onSubmit, handleFinish, ...props }
           if (!userInput.trim()) return;
           if (e.keyCode === 13) {
             if (e.shiftKey) {
+              e.preventDefault()
               setUserInput((state) => state + '\n');
               return;
             }