Update changelog for v2.7.1 release
## HEAD (Unreleased)
+## 2.7.1 (November 18, 2020)
+
- Error on delete if cluster is unreachable (https://github.com/pulumi/pulumi-kubernetes/pull/1379)
- Update pulumi deps to v2.13.2 (https://github.com/pulumi/pulumi-kubernetes/pull/1383)
