v0.16.0

• Bumped to latest https://github.com/google/starlark-go to get improved hash() per discussion in slack

e6345524ca9229d42828a2cd700557ced1d61f00655a09c9e2f1535c49dfd52b  ./ytt-darwin-amd64
611f0d0113a5b003021294ba97fdd2db3da5e85f33dc79122eaea3128ebe7d89  ./ytt-linux-amd64
912ce7a5729c414786e6b7cb1c938b62f08693ee15dd0c4b95c451817740d763  ./ytt-windows-amd64.exe

(Installation instructions: https://k14s.io/#install-from-github-release)