Update changelog for v3.19.4 release
## Unreleased
+## 3.19.4 (June 21, 2022)
+
- Use fully-qualified resource name for generating manifests, to avoid conflicts (https://github.com/pulumi/pulumi-kubernetes/pull/2007)
- Upgrade helm and k8s client-go module dependencies (https://github.com/pulumi/pulumi-kubernetes/pull/2008)
- Allow a user to opt-in to removing resources from Pulumi state when a cluster is unreachable (https://github.com/pulumi/pulumi-kubernetes/pull/2037)
