Add missing tinxyml dependency

I'm not able to build the package on my debian-sid system without installing TinyXML (version 1). Seems to be required https://salsa.debian.org/science-team/ros-urdf/-/blob/master/urdf/CMakeLists.txt?ref_type=heads#L11 but somehow is not present in d/control build-deps. Maybe previously any of the build-dep brought the libtinymxl-dev into the build and a recent upload probably removed it making now the ros-urdf to fail now.