Switch to iterator=True on python-gitlab

Since as_list will be deprecated soon, switch to the equivalent
iterator=True.

Signed-off-by: Walter Lozano <walter.lozano@collabora.com>

release-scripts/create-branches

@@ -202,7 +202,7 @@ class Brancher:
             projects.extend(p)
 
         total_pages = self.gl.projects.list(
-            as_list=False, per_page=per_page, **kwargs
+            iterator=True, per_page=per_page, **kwargs
         ).total_pages
         thread_pool(
             num_worker_threads, _fetch_page, range(1, total_pages + 1), num_retries=2

release-scripts/delete-branches

@@ -112,7 +112,7 @@ class Brancher:
             projects.extend(p)
 
         total_pages = self.gl.projects.list(
-            as_list=False, per_page=per_page, **kwargs
+            iterator=True, per_page=per_page, **kwargs
         ).total_pages
         thread_pool(
             num_worker_threads, _fetch_page, range(1, total_pages + 1), num_retries=2