Prepare for v3.18.1 release (#8480)

CHANGELOG.md

@@ -1,6 +1,43 @@
 CHANGELOG
 =========
 
+## 3.18.1 (2021-11-22)
+
+### Improvements
+
+- [cli] - When running `pulumi new https://github.com/name/repo`, check 
+  for branch `main` if branch `master` doesn't exist.
+  [#8463](https://github.com/pulumi/pulumi/pull/8463)
+
+- [codegen/python] - Program generator now uses `fn_output` forms where
+  appropriate, simplifying auto-generated examples.
+  [#8433](https://github.com/pulumi/pulumi/pull/8433)
+
+- [codegen/go] - Program generator now uses fnOutput forms where
+  appropriate, simplifying auto-generated examples.
+  [#8431](https://github.com/pulumi/pulumi/pull/8431)
+
+- [codegen/dotnet] - Program generator now uses `Invoke` forms where
+  appropriate, simplifying auto-generated examples.
+  [#8432](https://github.com/pulumi/pulumi/pull/8432)
+
+### Bug Fixes
+
+- [cli/nodejs] - Allow specifying the tsconfig file used in Pulumi.yaml.
+  [#8452](https://github.com/pulumi/pulumi/pull/8452)
+
+- [codegen/nodejs] - Respect default values in Pulumi object types.
+  [#8400](https://github.com/pulumi/pulumi/pull/8400)
+
+- [sdk/python] - Correctly handle version checking python virtual environments.
+  [#8465](https://github.com/pulumi/pulumi/pull/8465)
+
+- [cli] - Catch expected errors in stacks with filestate backends.
+  [#8455](https://github.com/pulumi/pulumi/pull/8455)
+
+- [sdk/dotnet] - Do not attempt to serialize unknown values.
+  [#8475](https://github.com/pulumi/pulumi/pull/8475)
+
 ## 3.18.0 (2021-11-17)
 
 ### Improvements