Allow parsing status.observedGeneration as string

[isugimpy]

Fix for fluxcd/flux2#4632

[souleb]

I have checked and ObservedGeneration is always an int64 in upstream Kubernetes and I believe in most common crds. It would be best if ArgoRollouts would just fix this, I think.

[isugimpy]

I agree, I've opened argoproj/argo-rollouts#3402 with them, but unfortunately I would anticipate that they're going to be unwilling to change it because this has been configured this way for 3 years. That said, this gives a little bit of safety wrapping their behavior and still allows things to work.