package/git: security bump to version 2.13.6
Release notes:
https://public-inbox.org/git/xmqqy3p29ekj.fsf@gitster.mtv.corp.google.com/
Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>