Add explicit mime dependency for Elixir < 1.10 (#666)
Add explicit mime dependency for Elixir < 1.10 (#666)

Mime is depended on by plug in the :test and :dev environments. CI
breaks on Elixir 1.9.4 if it picks mime 2.0.x. This patch explicitly
locks to mime ~> 1.0 on Elixir versions before 1.10.
appsignal/appsignal-elixir,appsignal/appsignal-elixir,appsignal/appsignal-elixir,appsignal/appsignal-elixir