Not to be merged before https://github.com/zed-industries/zed/pull/54550

This makes it so that we perform not all checks sequentially but in
parallel which should overall make this a lot faster.

Ultimately, we can save some more requests if we were to search for all
co-author looking PRs with one GraphQL query, but for now, this here
should make things a lot faster already whilst working fine with rate
limits.


Release Notes:

- N/A