fix: Useless assignment to local variable (#625)

close https://github.com/react-component/input-number/security/code-scanning/1

Author: afc163

src/InputNumber.tsx

@@ -455,7 +455,7 @@ const InternalInputNumber = React.forwardRef(
      */
     const flushInputValue = (userTyping: boolean) => {
       const parsedValue = getMiniDecimal(mergedParser(inputValue));
-      let formatValue: DecimalClass = parsedValue;
+      let formatValue: DecimalClass;
 
       if (!parsedValue.isNaN()) {
         // Only validate value or empty value can be re-fill to inputValue