* ensure that we compile the postcss nesting plugin
* re-add optional chaining
This will allow us to be 100% sure that we can safely call
hasOwnProperty in case we get some very strange objects.
This will now also be compiled/transpiled by esbuild.
* import the internal postcss nesting plugin
This allows us to work on it without re-compiling while running tests.
Just like we do with all other code.
* update changelog
