Credit new contributors.
Credit new contributors.

Thanks to @brettcannon, @felixonmars, and @kdart!

python-hyper/hyper-h2,Kriechi/hyper-h2,vladmunteanu/hyper-h2,bhavishyagopesh/hyper-h2,Kriechi/hyper-h2,vladmunteanu/hyper-h2,python-hyper/hyper-h2