add millen2223 to contributors

[millen2223]

I would like to continue contributing to GTN and Galaxy

[bebatut]

Hi @millen2223 Welcome to the GTN! Being on the contributor list is not a pre-requisite to contributing to the GTN.

So we do not add people to the contributor list until their first contribution to avoid inaccurately increasing our statistics. We will leave this pull request open until you make your first contribution and merge it then :)

If you are looking for ideas of how to contribute here, please take a look at this issue with contribution ideas, or have a chat with us on Gitter/Matrix :)

[millen2223]

@bebatut I understand, I made a request based on suggestion from @hexylena and @shiltemann here: #2973
In any other case I wouldn't dare to add myself here.
I am contributing since October and have multiple, although maybe small contributions
for example usegalaxy-eu/website#827 and here #2976 and others. At first I wanted to add it to those pull request but I haven't done it before, so I made a new pull request.

[hexylena]

Looks good, thanks @millen2223