fix getReactiveConnection() (#43)

RedisConnectionFactory cant castcannot be cask to ReactiveRedisConnection

opentracing-redis-spring-data2/src/main/java/io/opentracing/contrib/redis/spring/data2/connection/TracingRedisConnectionFactory.java

@@ -72,7 +72,7 @@ public DataAccessException translateExceptionIfPossible(RuntimeException e) {
   @Override
   public ReactiveRedisConnection getReactiveConnection() {
     if (delegate instanceof ReactiveRedisConnectionFactory) {
-      return new TracingReactiveRedisConnection((ReactiveRedisConnection) delegate,
+      return new TracingReactiveRedisConnection(((ReactiveRedisConnectionFactory) delegate).getReactiveConnection(),
           tracingConfiguration);
     }
     // TODO: shouldn't we throw an exception?