Update changelog for v2.8.2
## HEAD (Unreleased)
+## 2.8.2 (February 23, 2021)
+
- Postpone the removal of admissionregistration/v1beta1, which has been retargeted at 1.22 (https://github.com/pulumi/pulumi-kubernetes/pull/1474)
- Change k8s API removals from error to warning (https://github.com/pulumi/pulumi-kubernetes/pull/1475)
