Restore Spring Security dependency check for SpringSecurityDialect

See gh-31033

Author: terminux

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/thymeleaf/ThymeleafAutoConfiguration.java

@@ -53,6 +53,7 @@
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Import;
 import org.springframework.core.Ordered;
+import org.springframework.security.web.server.csrf.CsrfToken;
 import org.springframework.util.MimeType;
 import org.springframework.util.unit.DataSize;
 import org.springframework.web.servlet.resource.ResourceUrlEncodingFilter;
@@ -239,7 +240,7 @@ DataAttributeDialect dialect() {
 	}
 
 	@Configuration(proxyBeanMethods = false)
-	@ConditionalOnClass({ SpringSecurityDialect.class })
+	@ConditionalOnClass({ SpringSecurityDialect.class, CsrfToken.class })
 	static class ThymeleafSecurityDialectConfiguration {
 
 		@Bean