checkstyle: fix formatting

Author: alxkm

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

@@ -4,7 +4,6 @@
 import static org.junit.jupiter.api.Assertions.assertThrows;
 
 import java.util.stream.Stream;
-
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.Arguments;
@@ -28,4 +27,4 @@ void testFindNextSmallerElementsExceptions() {
         assertThrows(IllegalArgumentException.class, () -> NextSmallerElement.findNextSmallerElements(null));
     }
 
-}
+}