python-coherence: bump to the latest upstream commit

python-coherence: bump to the latest upstream commit

python-coherence is now orphaned, so unless a new maintainer
could be found, there is no ETA for the next release.

The setup.py file in the develop branch doesn't import other
Python packages, so no need for the build time dependencies.

This approach also fixes:

http://autobuild.buildroot.net/results/675/675721f773795987a2468daa33f299f7dc6ddb8a
http://autobuild.buildroot.net/results/cd9/cd99ac66af7a0cb24510bee78dd45884a8695776

Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>