Add `count_private` parameter to exclude private repositories

[Andrej123456789]

I have made a two discussions about this problem on the old repo and came to conclusion it would be nice to count only public repositories in language card. It is possible to exclude names of the repositories, but that leaks names of the repositories and EXCLUDE_REPO variable in Vercel deployment excludes said repositories from both "standard" and language cards which is not what I want. This feature existed some time in history.

There was pull request made on the old repo so I will reference it here just in case: anuraghazra#4888

[martin-mfg]

If I understand correctly, the proposed new parameter would exclude private commits in a situation where the current implementation includes them, right? I have changed the title of this issue accordingly.

[Andrej123456789]

Yes, the proposed new parameter would not look into private repositories for a language card if enabled.