add empty showMenu method to password manager class

src/main/java/PasswordManager.java

@@ -1,6 +1,7 @@
 public class PasswordManager implements PasswordManagerInterface {
     public static void main(String[] args) {
-        new PasswordManager();
+        PasswordManager pm = new PasswordManager();
+        pm.showMenu();
     }
 
     public PasswordManager() {
@@ -16,4 +17,9 @@ public class PasswordManager implements PasswordManagerInterface {
     public void openVault() {
 
     }
+
+    @Override
+    public void showMenu() {
+
+    }
 }

src/main/java/PasswordManagerInterface.java

@@ -3,4 +3,5 @@ public interface PasswordManagerInterface {
     };
     public void listVaults();
     public void openVault();
+    public void showMenu();
 }

src/test/java/PasswordManagerTest.java

@@ -27,4 +27,9 @@ class PasswordManagerTest {
     void openVault() {
         pm.openVault();
     }
+
+    @Test
+    void showMenu() {
+        pm.showMenu();
+    }
 }