bluetooth: remove unused gobject import

BUG=chromium:602461
TEST=CQ passes

Change-Id: I08f7a54066472298fe74feac31c1f5aac36a4bd3
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/autotest/+/2602556
Reviewed-by: Shyh-In Hwang <josephsih@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
diff --git a/client/cros/bluetooth/advertisement.py b/client/cros/bluetooth/advertisement.py
index ea0895f..c6a539e 100755
--- a/client/cros/bluetooth/advertisement.py
+++ b/client/cros/bluetooth/advertisement.py
@@ -16,7 +16,6 @@
 import dbus
 import dbus.mainloop.glib
 import dbus.service
-import gobject
 import logging