Fix typo: 4 -> 5

Confirmed with canonical data: https://github.com/exercism/problem-specifications/blob/master/exercises/sum-of-multiples/canonical-data.json#L6
that this test should be 3 and 5

exercises/sum-of-multiples/src/test/java/SumOfMultiplesTest.java

@@ -6,7 +6,7 @@ import static org.junit.Assert.*;
 public class SumOfMultiplesTest {
 
     @Test
-    public void testSumOfMultiplesOf3and4UpToOne() {
+    public void testSumOfMultiplesOf3and5UpToOne() {
 
         int[] set = {
                 3,