ClassCastException on Gradle 9: DependencyExtractorBuildService cannot cast to DependencyExtractor

Plugin 1.4.1 crashes on Gradle 9.1 with a classloader conflict:

```
java.lang.ClassCastException: class org.gradle.dependencygraph.extractor.DependencyExtractorBuildService$Inject_
cannot be cast to class org.gradle.dependencygraph.extractor.DependencyExtractor
(... in unnamed module of loader VisitableURLClassLoader @4d89edf3;
... in unnamed module of loader VisitableURLClassLoader @a7df2df)
```

Two different classloader instances load the service class vs the interface it's cast to. Likely caused by Gradle 9's classloader isolation changes.

Happens via both `gradle/actions/setup-gradle@v5` (`dependency-graph: generate-and-submit`) and `gradle/actions/dependency-submission@v5` with `dependency-graph-plugin-version: '1.4.1'`.

**Versions:** Gradle 9.1, plugin 1.4.1, gradle/actions v5.0.2, JDK 17

v1.4.1 release notes mention "Test plugin with Gradle 9.x" but it doesn't work in practice.