Clean CHANGELOG_PENDING.md after v3.16.0 release
### Improvements
-- [codegen/dotnet] - Add helper function forms `$fn.Invoke` that
- accept `Input`s, return an `Output`, and wrap the underlying
- `$fn.InvokeAsync` call. This change addreses
- [#5758](https://github.com/pulumi/pulumi/issues/) for .NET, making
- it easier to compose functions/datasources with Pulumi resources.
- NOTE for resource providers: the generated code requires Pulumi .NET
- SDK 3.15 or higher.
-
- [#7899](https://github.com/pulumi/pulumi/pull/7899)
-
-- [auto/dotnet] - Add `pulumi state delete` and `pulumi state unprotect` functionality
- [#8202](https://github.com/pulumi/pulumi/pull/8202)
### Bug Fixes
