Bump MacOS image for Azure Pipeline (#260)
Bump MacOS image for Azure Pipeline (#260)

The 10.13 image is being removed on 3/23.

https://devblogs.microsoft.com/devops/removing-older-images-in-azure-pipelines-hosted-pools/
syoyo/tinyobjloader,syoyo/tinyobjloader,syoyo/tinyobjloader,syoyo/tinyobjloader