ChangeIT: Fix raw type warning

Change-Id: If76979c4604a97c1e48be366aed5eb127a06bc63
diff --git a/gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/api/change/ChangeIT.java b/gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/api/change/ChangeIT.java
index 3bd75c9..c11474f 100644
--- a/gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/api/change/ChangeIT.java
+++ b/gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/api/change/ChangeIT.java
@@ -3379,7 +3379,7 @@
 
   private void modifySubmitRules(String newContent) throws Exception {
     try (Repository repo = repoManager.openRepository(project)) {
-      TestRepository testRepo = new TestRepository<>((InMemoryRepository) repo);
+      TestRepository<?> testRepo = new TestRepository<>((InMemoryRepository) repo);
       testRepo
           .branch(RefNames.REFS_CONFIG)
           .commit()