Use native nodejs 20 .env support

[mihaiplesa]

We're currently using https://www.npmjs.com/package/dotenv to override npm config values.

Coming in v20.6.0 (nodejs/node#48890) this will be native functionality.

[mihaiplesa]

@goodov do we still want this?

[goodov]

we don't use .env to populate process.env, so the native implementation doesn't do anything for us.