Fix return type for ExUnit.OnExitHandler.register/1 (#9968)
Fix return type for ExUnit.OnExitHandler.register/1 (#9968)


ggcampinho/elixir,pedrosnk/elixir,elixir-lang/elixir,kelvinst/elixir,joshprice/elixir,kelvinst/elixir,michalmuskala/elixir,ggcampinho/elixir,kimshrier/elixir,kimshrier/elixir,pedrosnk/elixir