urdfdom_py: 0.2.9-4 in 'hydro/release.yaml' [bloom]

Increasing version of package(s) in repository `urdfdom_py`:
- previous version: `0.2.9-2`
- new version: `0.2.9-4`
- distro file: `hydro/release.yaml`
- bloom version: `0.4.4`