restore dropdown button ref callback to return undefined

This was over-reverted with 5d137d8

Author: nbogie

src/components/Dropdown/index.tsx

@@ -152,7 +152,9 @@ export const Dropdown = ({
           </div>
           <button
             onClick={() => handleOptionClick(option)}
-            ref={(el) => (optionRefs.current[index] = el as HTMLButtonElement)}
+            ref={(el) => {
+              optionRefs.current[index] = el as HTMLButtonElement;
+            }}
             onBlur={handleBlur}
           >
             <span>{option.label}</span>