Sync versions: filter by type on update

If two versions share the same verbose name
(a branch named 2.0 and a tag named 2.0),
then we will be updating both,
instead of just one and changing its type from branch to tag.
Later when running this same code,
it will see the branch as new, since isn't included in our queryset that
filters by type=branch.

This wasn't happening before because this check was true
https://github.com/readthedocs/readthedocs.org/blob/2e3f208c4906de649a9b5b9e33afee6cc20b86bc/readthedocs/api/v2/utils.py#L74-L74

Since a branch would never change its identifier
(origin/name), but once lsremote was enabled,
the identifier didn't included the 'origin/' part.

So, when doing a full build the branches would be changed
to (origin/name) and when doing a syn they would be changed
to (name), and so on.

Ref #8992 (comment)

Author: stsewd

readthedocs/api/v2/utils.py

@@ -79,9 +79,9 @@ def sync_versions_to_db(project, versions, type):  # pylint: disable=redefined-b
             Version.objects.filter(
                 project=project,
                 verbose_name=version_name,
+                type=type,
             ).update(
                 identifier=version_id,
-                type=type,
                 machine=False,
             )