chore: update to HAL Explorer 2.1.0

Author: toedter

spring-data-rest-hal-explorer/pom.xml

@@ -13,7 +13,7 @@
 	<name>Spring Data REST - HAL Explorer</name>
 
 	<properties>
-		<explorer.version>1.2.3</explorer.version>
+		<explorer.version>2.1.0</explorer.version>
 		<java-module-name>spring.data.rest.hal.explorer</java-module-name>
 		<!--
 			Skip Javadoc as there's no public code to document