Deprecated dependency found inside of old magic string package

Hi there, love this package.

I am getting a deprecation warning however. 

Offending package: https://github.com/Rich-Harris/sourcemap-codec

It is used in the older version of the included magic-string module inside of this package.json.

Could you please update magic-string version, which will in turn use the updated dependency: https://github.com/jridgewell/sourcemap-codec

Thanks!