Python 2 is EOL at the end of 2019, so don't depend on it anymore.
Remove pychart support, because upstream is dead and there is no python3
version. We were only using it for one graph, and that has been
replaced in osmo-bsc I36b721f895caee9766528e14d854b6aa2a2fac85.
Depends: osmo-bsc I36b721f895caee9766528e14d854b6aa2a2fac85
As seen by https://packages.debian.org, python-nwdiag is only available
in buster and older stables, while python3-nwdiag is available in both
old and new releases as well as testing and unstable.
Depends: osmo-ci I0ebee6ac11df779ab954bd6648a0bebefc3350a2
Remove git from depends, because it isn't needed when building the
manuals from a source tarball. Avoid having git in the build
dependencies of the upcoming manuals packaging for debian.
Make it possible to run the dependency check without the Makefile. This
is needed to split up the manual pages into the projects repositories,
so we can call check-depends.sh from there.