DEVELOPERS: remove package/sepolgen/

DEVELOPERS: remove package/sepolgen/

The directory package/sepolgen/ was removed in commit 9d6da7a26
(policycoreutils: split packages and bump to 2.7), but two
entries were left in the DEVELOPERS file.

This causes the following warnings when running util/get-developers:
WARNING: 'package/sepolgen/' doesn't match any file
WARNING: 'package/sepolgen/' doesn't match any file

Remove the erroneous entries.

Signed-off-by: Cam Hutchison <camh@xdna.net>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>