Didn't support :via tuples as broadway names

[Kevin Pan]

The new version of Broadway is allowed :via tuples as broadway names.

But the code of Dashboard are not support for it current:

broadway_dashboard/lib/broadway_dashboard.ex

Line 56 in 5bddcee

 case Enum.filter(pipelines, &is_atom/1) do 

I hope this feature will be supported soon, Many thanks.

[José Valim]

Not in our plans at the moment but we are glad to accept contributions!