update »Spring Boot 3« example to 3.2.3

samples/spring-boot3/pom.xml

@@ -7,7 +7,7 @@
     <parent>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-parent</artifactId>
-        <version>3.2.2</version>
+        <version>3.2.3</version>
         <relativePath/> <!-- lookup parent from repository -->
     </parent>