Move to ESM

[Patrick-Clausen]

Hi,

Would you be open to a PR that migrates this package to the ESM syntax, so that this module may be tree-shakable in other packages that depend on it?

I would be willing to make the change myself, I am mainly interested in whether you are open to the change / whether this package is still maintained.

[Patrick-Clausen]

I opened a PR with an example solution with backwards compatibility for those that depend on this through commonjs imports.