sync: PersistentTransport call parent init

Found via pylint:
  W0231: __init__ method from base class 'Transport'
  is not called (super-init-not-called)

Just fixed for code correctness and to avoid potential future bugs.

Change-Id: Ie1e723c2afe65d026d70ac01a16ee7a40c149834
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/390676
Reviewed-by: Mike Frysinger <vapier@google.com>
Tested-by: Daniel Kutik <daniel.kutik@lavawerk.com>
Commit-Queue: Daniel Kutik <daniel.kutik@lavawerk.com>

subcmds/sync.py

diff --git a/subcmds/sync.py b/subcmds/sync.py
index 9e43df4..a0a0be9 100644
--- a/subcmds/sync.py
+++ b/subcmds/sync.py
@@ -2043,6 +2043,7 @@
 # is passed during initialization.
 class PersistentTransport(xmlrpc.client.Transport):
     def __init__(self, orig_host):
+        super().__init__()
         self.orig_host = orig_host
 
     def request(self, host, handler, request_body, verbose=False):