fix(frontend): unable multiple enter on search page (#2074)

# Description

Please include a summary of the changes and the related issue. Please
also include relevant motivation and context.

## Checklist before requesting a review

Please delete options that are not relevant.

- [ ] My code follows the style guidelines of this project
- [ ] I have performed a self-review of my code
- [ ] I have commented hard-to-understand areas
- [ ] I have ideally added tests that prove my fix is effective or that
my feature works
- [ ] New and existing unit tests pass locally with my changes
- [ ] Any dependent changes have been merged

## Screenshots (if appropriate):

frontend/lib/components/ui/SearchBar/SearchBar.tsx

@@ -25,14 +25,16 @@ export const SearchBar = (): JSX.Element => {
   }, [setCurrentBrainId, message]);
 
   const submit = async (): Promise<void> => {
-    setSearching(true);
-    setMessages([]);
-    try {
-      await addQuestion(message);
-    } catch (error) {
-      console.error(error);
-    } finally {
-      setSearching(false);
+    if (!searching) {
+      setSearching(true);
+      setMessages([]);
+      try {
+        await addQuestion(message);
+      } catch (error) {
+        console.error(error);
+      } finally {
+        setSearching(false);
+      }
     }
   };