Platform on OSX may start with macos (#444)
Platform on OSX may start with macos (#444)

Platform name using python 3.8: macOS-10.14.6-x86_64-i386-64bit

Signed-off-by: Shane Loretz<7fde345e8e2e22c78a1570a4807e4629866dc7de@openrobotics.org>
Signed-off-by: Shane Loretz <7fde345e8e2e22c78a1570a4807e4629866dc7de@osrfoundation.org>
ros2/ci,ros2/ci,ros2/ci