update project structure

app/src/test/kotlin/day01/Day01Test.kt

@@ -1,4 +1,4 @@
-package org.example
+package day01
 
 import kotlin.test.Test
 import kotlin.test.assertNotNull

app/src/test/kotlin/org/example/AppTest.kt

@@ -1,14 +0,0 @@
-/*
- * This source file was generated by the Gradle 'init' task
- */
-package org.example
-
-import kotlin.test.Test
-import kotlin.test.assertNotNull
-
-class AppTest {
-    @Test fun appHasAGreeting() {
-        val classUnderTest = App()
-        assertNotNull(classUnderTest.greeting, "app should have a greeting")
-    }
-}