`svelte-package` doesn't include source maps

[DetachHead]

Describe the bug

when running svelte-package, it does not include source maps even when they are enabled in svelte.config.js

Reproduction

// svelte.config.js
import preprocess from 'svelte-preprocess';

const config = {
  compilerOptions: {
    enableSourcemap: true,
  },
  preprocess: preprocess({
    sourceMap: true,
  }),
};

export default config;

Logs

No response

System Info

System:
    OS: Windows 10 10.0.19044
    CPU: (12) x64 11th Gen Intel(R) Core(TM) i5-11500T @ 1.50GHz
    Memory: 672.74 MB / 15.73 GB
  Binaries:
    Node: 18.10.0 - C:\Program Files\nodejs\node.EXE
    npm: 8.19.2 - C:\Program Files\nodejs\npm.CMD
  Browsers:
    Edge: Spartan (44.19041.1266.0), Chromium (105.0.1343.33)
    Internet Explorer: 11.0.19041.1566

Severity

annoyance

Additional Information

the src and the package created by svelte-package: