Seems always tries to fetch from the master branch

Using https://github.com/kesla/get-package-json-from-github/blob/master/lib/index.js and we often need `main` branch

Start by reading the referenced lib/index.js in kesla/get-package-json-from-github and trace where the branch is selected for fetching package data. Done means the badge script can fetch from the main branch instead of always using master; verify the affected fetch behavior against the repository's available checks.

Written by the indexing model from the issue text.