k8s go packages are pinned to 1.16 and should be upgraded

[acookin]

The go packages used by the operator are pinned to 1.16, which is now dropped out of the support window.

At "some point", these will be incompatible with supported versions of kubernetes, so this is essentially a ticking time bomb.

I think this is pinned because of the old version of the operator-sdk this project was generated from, and upgrading from a 0.X to a 1.X version of this tool is a fairly large set of work, as they've introduced a number of breaking changes.

Before taking on this work, we should decide what the maintenance story is around the operator.