Pinning k8s to a specific release

The other Kubernetes dependencies, such as client-go and apimachinery,
are pinned to 1.14.1 but Kubernetes itself was tracking the tip of the
1.14 release branch and picking up changes between releases. This
change pins Kubernetes to the same version as the other parts of it.

Signed-off-by: Matt Farina <matt@mattfarina.com>