Bump k8s.io/ dependencies to 1.16.8

[wongma7]

Bump for hygiene and to pick up a newer klog with logtostderr default true.

Details on klog issue:

While working on #303, I ran into crashes like this that happen if you go down some code path where klog tries to log something:

W0317 00:35:43.672444       1 client_config.go:539] Neither --kubeconfig nor --master was specified.  Using the inClusterConfig.  This might not work.                                          
log: exiting because of error: log: cannot create log: open /tmp/aws-iam-authenticator.ip-172-31
-16-168.aws-iam-authenticator.log.WARNING.20200317-003543.1: no such file or directory

The fix is to either set klog.logtostderr true somewhere in the code or to bump klog to a version where it defaults true. Personally prefer to bump.

[k8s-ci-robot]

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[nckturner]

/lgtm