Update the CHANGELOG for v1.7.1
CHANGELOG
=========
-## Master (unreleased)
+## 1.7.1 (2019-12-13)
- Fix [SxS issue](https://github.com/pulumi/pulumi/issues/3652) introduced in 1.7.0 when assigning
`Output`s across different versions of the `@pulumi/pulumi` sdk
