Implementation of test class review comments

Author: t-sormonte

src/main/java/org/prebid/server/bidder/sparteo/SparteoBidder.java

@@ -126,9 +126,8 @@ private Site modifySite(Site site, String siteNetworkId, JacksonMapper mapper) {
         }
 
         final Publisher publisher = site.getPublisher();
-        final ExtPublisher extPublisher;
 
-        extPublisher = publisher.getExt() != null
+        final ExtPublisher extPublisher = publisher.getExt() != null
                 ? publisher.getExt()
                 : ExtPublisher.empty();