Attempt to fix Windows build error

See gh-33766

Author: philwebb

buildSrc/src/main/java/org/springframework/boot/build/antora/GenerateAntoraPlaybook.java

@@ -135,7 +135,7 @@ private Map<String, Object> createContentSource() {
 		Path playbookPath = getOutputFile().get().getAsFile().toPath().getParent();
 		Path antoraSrc = getProjectPath(getProject()).resolve(ANTORA_SOURCE_DIR);
 		StringBuilder url = new StringBuilder(".");
-		relativizeFromRootProject(playbookPath).normalize().forEach((path) -> url.append("/.."));
+		relativizeFromRootProject(playbookPath).normalize().forEach((path) -> url.append(File.separator).append(".."));
 		source.put("url", url.toString());
 		source.put("branches", "HEAD");
 		source.put("version", getProject().getVersion().toString());
@@ -159,7 +159,7 @@ private void addAntoraContentStartPaths(Set<String> startPaths) {
 	private void addDir(Map<String, Object> data) {
 		Path playbookDir = toRealPath(getOutputFile().get().getAsFile().toPath()).getParent();
 		Path outputDir = toRealPath(getProject().getBuildDir().toPath().resolve("site"));
-		data.put("output", Map.of("dir", "./" + playbookDir.relativize(outputDir).toString()));
+		data.put("output", Map.of("dir", "." + File.separator + playbookDir.relativize(outputDir).toString()));
 	}
 
 	@SuppressWarnings("unchecked")

buildSrc/src/test/java/org/springframework/boot/build/antora/GenerateAntoraPlaybookTests.java

@@ -46,11 +46,12 @@ void writePlaybookGeneratesExpectedContent() throws Exception {
 			task.getXrefStubs().addAll("appendix:.*", "api:.*", "reference:.*");
 			task.getAlwaysInclude().set(Map.of("name", "test", "classifier", "local-aggregate-content"));
 		});
-		Path actual = this.temp.toPath()
-			.resolve("rootproject/project/build/generated/docs/antora-playbook/antora-playbook.yml");
-		System.out.println(Files.readString(actual));
-		assertThat(actual).hasSameTextualContentAs(
-				Path.of("src/test/resources/org/springframework/boot/build/antora/expected-playbook.yml"));
+		String actual = Files.readString(this.temp.toPath()
+			.resolve("rootproject/project/build/generated/docs/antora-playbook/antora-playbook.yml"));
+		String expected = Files
+			.readString(Path.of("src/test/resources/org/springframework/boot/build/antora/expected-playbook.yml"));
+		System.out.println(actual);
+		assertThat(actual).isEqualToNormalizingNewlines(expected);
 	}
 
 	private void writePlaybookYml(ThrowingConsumer<GenerateAntoraPlaybook> customizer) throws Exception {