Bump dev.zacsweers.kctfork:core from 0.2.1 to 0.4.0

Bumps [dev.zacsweers.kctfork:core](https://github.com/zacsweers/kotlin-compile-testing) from 0.2.1 to 0.4.0.
- [Release notes](https://github.com/zacsweers/kotlin-compile-testing/releases)
- [Changelog](https://github.com/ZacSweers/kotlin-compile-testing/blob/main/CHANGELOG.md)
- [Commits](ZacSweers/kotlin-compile-testing@0.2.1...0.4.0)

---
updated-dependencies:
- dependency-name: dev.zacsweers.kctfork:core
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

compiler-plugin/build.gradle.kts

@@ -31,7 +31,7 @@ dependencies {
     compileOnly("com.google.auto.service:auto-service:$autoService")
     kapt("com.google.auto.service:auto-service:$autoService")
     compileOnly("org.jetbrains.kotlin:kotlin-compiler-embeddable:1.9.10")
-    testImplementation("dev.zacsweers.kctfork:core:0.2.1")
+    testImplementation("dev.zacsweers.kctfork:core:0.4.0")
     testImplementation("junit:junit:4.13.2")
     testImplementation("com.google.truth:truth:1.1.5")
     testImplementation(kotlin("reflect"))