hardcoded "github.com" in build script

[Hugo-Trentesaux]

Trying to use build script outside of github, failing on this:

https://github.com/polkadot-js/dev/blob/master/packages/dev/scripts/polkadot-dev-build-ts.mjs#L1421-L1423

const repoPath = pkg.repository.url
  .split('https://github.com/')[1]
  .split('.git')[0];

🤮