Upgrade to Spring Asciidoctor Extensions 0.4.0.RELEASE

Closes gh-20041

Author: wilkinsona

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/pom.xml

@@ -298,8 +298,8 @@
 							</dependency>
 							<dependency>
 								<groupId>io.spring.asciidoctor</groupId>
-								<artifactId>spring-asciidoctor-extensions</artifactId>
-								<version>0.1.3.RELEASE</version>
+								<artifactId>spring-asciidoctor-extensions-block-switch</artifactId>
+								<version>0.4.0.RELEASE</version>
 							</dependency>
 						</dependencies>
 					</plugin>