Upgrade to Thymeleaf Layout Dialect 1.4.0

Closes gh-5955

spring-boot-dependencies/pom.xml

@@ -169,7 +169,7 @@
 		<thymeleaf.version>2.1.4.RELEASE</thymeleaf.version>
 		<thymeleaf-extras-springsecurity4.version>2.1.2.RELEASE</thymeleaf-extras-springsecurity4.version>
 		<thymeleaf-extras-conditionalcomments.version>2.1.1.RELEASE</thymeleaf-extras-conditionalcomments.version>
-		<thymeleaf-layout-dialect.version>1.3.3</thymeleaf-layout-dialect.version>
+		<thymeleaf-layout-dialect.version>1.4.0</thymeleaf-layout-dialect.version>
 		<thymeleaf-extras-data-attribute.version>1.3</thymeleaf-extras-data-attribute.version>
 		<thymeleaf-extras-java8time.version>2.1.0.RELEASE</thymeleaf-extras-java8time.version>
 		<tomcat.version>8.0.33</tomcat.version>