devel/busd: update to 0.3.0

Changes: https://github.com/dbus2/busd/releases/tag/0.3.0
Reported by: GitHub (watch releases)

(cherry picked from commit a6a8cadce02a2f71a4b2a6b0d243e14297d1f5dd)
(cherry picked from commit 16ff52cdef251e57c04759bb8d3934076333a215)
(cherry picked from commit 0bdbff31c50d12c07ba5370bf524d8ea86f9097a)
(cherry picked from commit 744faa81ea34f98530699b2893142e63aba070c9)