fix: remove var usage

Use class instead of var to be java 8-compliant

Author: Nico-DF

spring-shell-core/src/main/java/org/springframework/shell/component/NumberInput.java

@@ -127,7 +127,7 @@ protected boolean read(BindingReader bindingReader, KeyMap<String> keyMap, Numbe
 				checkInput(input, context);
 				break;
 			case OPERATION_EXIT:
-				var num = parseNumber(context.getInput());
+				Number num = parseNumber(context.getInput());
 
 				if (num != null) {
 					context.setResultValue(parseNumber(context.getInput()));