Rename issue 215 test

Author: jhalterman

src/test/java/dev/failsafe/issues/Issue215.java renamed to src/test/java/dev/failsafe/issues/Issue215Test.java

@@ -6,7 +6,7 @@
 import java.time.Duration;
 
 @Test
-public class Issue215 {
+public class Issue215Test {
   public void test() {
     RetryPolicy.builder()
       .withBackoff(Duration.ofNanos(Long.MAX_VALUE).minusSeconds(1), Duration.ofSeconds(Long.MAX_VALUE), 1.50);