fix ProjectWithFeaturePreviewSpec

Author: snazy

src/funcTest/resources/java-project-with-feature-previews/build.gradle

@@ -25,6 +25,7 @@ repositories {
 // Configure Java compilation tasks to enable feature previews
 tasks.withType(JavaCompile).configureEach {
     options.compilerArgs.add("--enable-preview")
+    options.release = 22
     javaCompiler.set(javaToolchains.compilerFor {
         // Using 15 so that we can try a feature preview
         languageVersion.set(JavaLanguageVersion.of(22))