debian: Fix packaging by requiring python-minimal

We require the python2 binary to generate code. In Debian this
is provided by python-minimal. Add it to the build-depends to
fix building packages.

Change-Id: Iaa26f4331966d015b193d2ab1e34621b1e319ef1
Reviewed-on: https://gerrit.osmocom.org/37
Tested-by: Jenkins Builder
Reviewed-by: Holger Freyther <holger@freyther.de>
1 file changed