bump to go-jsonnet v0.16.0 after accidentally reverting back to go-jsonnet v0.15.0 in #292 (released in kubecfg v0.18.0).
Bumping to v0.16.0 instead of directly to v0.17.0 because some users reported a backward compat breakage in go-jsonnet 0.17.0, so giving them a chance to run v0.16.0 for a bit but with the improved kube-api clients that came with kubecfg v0.18.0