Fix .toStream deprecation warning

Fixes following warning:
method toStream in trait IterableOnceOps is deprecated (since 2.13.0): Use .to(LazyList) instead of .toStream

Change-Id: I5c1aea873d7a6f08d34a9e4a18e0133150fb8de1

src/main/scala/com/googlesource/gerrit/plugins/analytics/Contributors.scala

diff --git a/src/main/scala/com/googlesource/gerrit/plugins/analytics/Contributors.scala b/src/main/scala/com/googlesource/gerrit/plugins/analytics/Contributors.scala
index 5047805..37006ca 100644
--- a/src/main/scala/com/googlesource/gerrit/plugins/analytics/Contributors.scala
+++ b/src/main/scala/com/googlesource/gerrit/plugins/analytics/Contributors.scala
@@ -147,7 +147,7 @@
 
       histogram.get(repo, new AggregatedHistogramFilterByDates(startDate, stopDate, branchesExtractor, aggregationStrategy))
         .flatMap(aggregatedCommitActivity => UserActivitySummary.apply(stats)(aggregatedCommitActivity))
-        .toStream
+        .to(LazyList)
     }
   }
 }