Fixed wildcard imports

Author: Andruid929

src/test/java/com/thealgorithms/stacks/StackUsingLinkedListTest.java

@@ -1,6 +1,10 @@
 package com.thealgorithms.stacks;
 
-import static org.junit.jupiter.api.Assertions.*;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
@@ -76,4 +80,4 @@ void size() {
 
         assertEquals(2, linkedStack.size());
     }
-}
+}