Unify Outreachy channel
We are using the same artwork for every year, so there's no point on bumping the images.
I also made sure that all the references to opw2019=1
got updated to outreachy=1
.
The program's name and URL has also been updated.
I'm an Outreachy coordinator for GNOME https://www.outreachy.org/communities/cfp/gnome/coordinator/preview/felipeborges/