How to: Kubernetes upgrade fails due to `PodDisruptionBudget`
To work around this remove these `PodDisruptionBudget`s for the time of the upgrade.
You can most easily find them via the `k9s` pdb overview of this resource, alternatively with this command:

```
$ kubectl get --all-namespaces PodDisruptionBudget
```

As of now the following `PodDisruptionBudget`s are problematic in the upgrade
context, all due to the `minAvailable` attribute:

- **eventing-webhook** from _knative-eventing_
- **activator-pdb** from _knative-serving_
- **webhook-pdb** from _knative-serving_