Meson >= 0.64.0 started to validate type of objects passed to the
dependencies: kwarg and GStreamer was passing a few invalid args that
should have been in
dependencies: is for libraries that the doc generator needs to link
against. It doesn't make much sense to pass things like a gir target or
an executable to it.
depends: is for any type of target that needs to be built before we
generate the doc. That should be used for gir, the doc cache, etc.