fix modifying the runtime classpath of the run task

src/main/kotlin/dev/frogmc/phytotelma/run/task/RunGameTask.kt

@@ -111,7 +111,7 @@ abstract class RunGameTask @Inject constructor(env: Env) : JavaExec() {
     }
 
     override fun exec() {
-        super.setClasspath(project.files())
+        super.setClasspath(classpath)
         workingDir = project.projectDir.resolve("run")
         super.exec()
     }