Fix runDistributable on Windows (#435)

Resolves #378

gradle-plugins/compose/src/main/kotlin/org/jetbrains/compose/desktop/application/tasks/AbstractRunDistributableTask.kt

@@ -43,7 +43,7 @@ abstract class AbstractRunDistributableTask @Inject constructor(
 
         execOperations.exec { spec ->
             spec.workingDir(workingDir)
-            spec.executable(executable)
+            spec.executable(workingDir.resolve(executable).absolutePath)
         }.assertNormalExitValue()
     }
 }