Fix umbrella test count

[luc-tielen]

No description provided.

[coveralls]

Coverage increased (+2.2%) to 75.789% when pulling 82e8822 on luc-tielen:fix_umbrella_test_count into a876a73 on parroty:master.

[luc-tielen]

Fixes #33.

Looks like tests in CI build fail because of following reason:
** (UndefinedFunctionError) undefined function: MapSet.new/1
when doing mix deps.get (package jsx)

(But when running locally they are fine for me.)
@parroty or @myronmarston can you re-run/verify manually?

[luc-tielen]

So, any updates on this @parroty? Been almost a week now.
If the build failure is a problem, it's an error in hex for Elixir version 1.1.1, due to MapSet.new not being available there.
Maybe a separate issue should be created to fix it (and potentially add other more recent versions of Elixir too.)

[parroty]

Thanks and very sorry taking time to merge.

[luc-tielen]

No problem, glad it got merged in :)