Fix deprecation warnings

Author: mhalbritter

start-site/src/test/java/io/spring/start/site/extension/dependency/springrestdocs/SpringRestDocsMavenBuildCustomizerTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -41,7 +41,7 @@ void customizesGradleBuild() {
 		assertThat(build.plugins().values()).singleElement().satisfies((plugin) -> {
 			assertThat(plugin.getGroupId()).isEqualTo("org.asciidoctor");
 			assertThat(plugin.getArtifactId()).isEqualTo("asciidoctor-maven-plugin");
-			assertThat(plugin.getVersion()).isEqualTo("2.2.1");
+			assertThat(plugin.getVersionReference().getValue()).isEqualTo("2.2.1");
 			assertThat(plugin.getExecutions()).hasSize(1);
 			Execution execution = plugin.getExecutions().get(0);
 			assertThat(execution.getId()).isEqualTo("generate-docs");
@@ -60,7 +60,7 @@ void customizesGradleBuild() {
 			Dependency dependency = plugin.getDependencies().get(0);
 			assertThat(dependency.getGroupId()).isEqualTo("org.springframework.restdocs");
 			assertThat(dependency.getArtifactId()).isEqualTo("spring-restdocs-asciidoctor");
-			assertThat(dependency.getVersion()).isEqualTo("${spring-restdocs.version}");
+			assertThat(dependency.getVersionReference().getValue()).isEqualTo("${spring-restdocs.version}");
 		});
 	}