Update PrimeCalculatorTest.java

exercises/nth-prime/src/test/java/PrimeCalculatorTest.java

         assertThat(primeCalculator.nth(1), is(2));
     }
 
-    @@Ignore("Remove to run test")
+    @Ignore("Remove to run test")
     @Test
     public void testSecondPrime() {
         assertThat(primeCalculator.nth(2), is(3));
     }
 
-    @@Ignore("Remove to run test")
+    @Ignore("Remove to run test")
     @Test
     public void testSixthPrime() {
         assertThat(primeCalculator.nth(6), is(13));
     }
 
-    @@Ignore("Remove to run test")
+    @Ignore("Remove to run test")
     @Test
     public void testBigPrime() {
         assertThat(primeCalculator.nth(10001), is(104743));
     }
 
-    @@Ignore("Remove to run test")
+    @Ignore("Remove to run test")
     @Test
     public void testUndefinedPrime() {
         thrown.expect(IllegalArgumentException.class);