manifest.py: remove redundant import line

The import oe.package_manager line is redundant, let's remove it.

(From OE-Core rev: ade1f3ce34489bba5a7ab23793c1d82559150583)

Signed-off-by: Hongxu Jia <hongxu.jia@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/lib/oe/manifest.py

@@ -1,5 +1,4 @@
 from abc import ABCMeta, abstractmethod
-from oe.package_manager import *
 import os
 import re
 import bb