diamond: add version comment

exercises/diamond/src/test/java/DiamondPrinterTest.java

 import static org.hamcrest.CoreMatchers.is;
 import static org.junit.Assert.assertThat;
 
+/*
+ * version: 1.0.0
+ */
 public class DiamondPrinterTest {
+
     private DiamondPrinter diamondPrinter;
-    
+
     @Before
     public void setUp() {
         diamondPrinter = new DiamondPrinter();
     }
-        
+
     @Test
     public void testOneByOneDiamond() {
         List<String> output = diamondPrinter.printToList('A');