java/2016/20: add answer for test for part 2

Author: saser

java/src/test/java/com/github/saser/adventofcode/year2016/day20/Day20Test.java

@@ -30,7 +30,7 @@ public void part1Actual() throws IOException {
      @Test
      public void part2Actual() throws IOException {
          try (var input = new FileReader("inputs/2016/20")) {
-             var output = "";
+             var output = "113";
              var result = Day20.part2(input);
              Assert.assertEquals("no error", "", result.error);
              Assert.assertEquals("correct output", output, result.answer);