Forgot to add test file

Author: JAPNITSINGH

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

@@ -0,0 +1,8 @@
+package com.thealgorithms.sorts;
+
+public class SmoothSortTest extends SortingAlgorithmTest {
+    @Override
+    SortAlgorithm getSortAlgorithm() {
+        return new SmoothSort();
+    }
+}