fix(rspeedy/core): avoid pre-publish build (#479)

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## Summary

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problem or issue does this pull request resolve? -->

Fix an regression of #478: "error TS2307: Cannot find module
'@lynx-js/rspeedy/register' or its corresponding type declarations."

>
https://github.com/lynx-family/lynx-stack/actions/runs/14280496355/job/40029566753

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## Checklist

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- [ ] Tests updated (or not required).
- [ ] Documentation updated (or not required).

Author: colinaaa

packages/rspeedy/core/package.json

@@ -48,7 +48,6 @@
   "scripts": {
     "api-extractor": "api-extractor run --verbose",
     "build": "rslib build",
-    "prepublishOnly": "rslib build",
     "test": "pnpm -w run test --project rspeedy",
     "test:type": "vitest --typecheck.only"
   },