style: fix trailing blank line to satisfy clang-format

Author: anshullakra007

src/test/java/com/thealgorithms/sorts/ConcurrentMergeSortTest.java

@@ -90,5 +90,4 @@ public void testNullArray() {
         ConcurrentMergeSort.sort(array);
         org.junit.jupiter.api.Assertions.assertNull(array, "Null array should be handled without errors.");
     }
-
 }