Remember to return True on successful piper init

Showing a false-positive due to lack of a return.

Signed-off-by: Konstantin Ryabitsev <konstantin@linuxfoundation.org>
diff --git a/grokmirror/pi_piper.py b/grokmirror/pi_piper.py
index 5d5bbfb..69b6627 100755
--- a/grokmirror/pi_piper.py
+++ b/grokmirror/pi_piper.py
@@ -78,6 +78,7 @@
         fh.write(latest)
     if shallow:
         reshallow(repo, latest)
+    return True
 
 
 def run_pi_repo(repo: str, pipedef: str, dryrun: bool = False, shallow: bool = False,