refactor storage test for windows systems

src/test/java/StorageTest.java

@@ -14,6 +14,10 @@ class StorageTest {
     @BeforeAll
     static void init() {
         storage = new Storage();
+
+        if (System.getProperty("os.name").toLowerCase().contains("win")) {
+            testFilePath = "C:\\test.txt";
+        }
     }
 
     @AfterAll