Automatically add champions label

[mpadge]

Identify GitHub handles of champions from https://github.com/ropensci/roweb3/blob/main/data/team/champions.json. When GitHub handle of main submitting author matches on of those, add a "champions" label to the issue.

@yabellini This should add the label if and only if the "Submitting Author" is or was a champion:

Submitting Author Github Handle: <!--author1-->@github_handle<!--end-author1-->
Other Package Authors Github handles: (comma separated, delete if none) <!--author-others-->@github_handle1, @github_handle2<!--end-author-others-->

But it would ignore "Other Package Authors". Does that seem okay to you? We could of course also look for matches in "Other Package Authors", but that might mis-identify somehow?

[mpadge]

ropensci-org/buffy#123

[yabellini]

Looks good. If the submission is under the champions program, then the submitting author should be the champion, so the logic is correct. Thanks!