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<sloretz@openrobotics.org>
Signed-off-by: Shane Loretz <sloretz@osrfoundation.org>

ros2_batch_job/__main__.py

@@ -459,7 +459,7 @@ def run(args, build_function, blacklisted_package_names=None):
         args.os = 'linux'
         from .linux_batch import LinuxBatchJob
         job = LinuxBatchJob(args)
-    elif args.os == 'osx' or platform_name.startswith('darwin'):
+    elif args.os == 'osx' or platform_name.startswith('darwin') or platform_name.startswith('macos'):
         args.os = 'osx'
         from .osx_batch import OSXBatchJob
         job = OSXBatchJob(args)