Merge branch 'chore/ci-speedup' into 'develop'

CI: Replace mix test and mix coveralls with just mix coveralls

See merge request pleroma/pleroma!1235

.gitlab-ci.yml

@@ -52,8 +52,7 @@ unit-testing:
     - mix deps.get
     - mix ecto.create
     - mix ecto.migrate
-    - mix test --trace --preload-modules
-    - mix coveralls
+    - mix coveralls --trace --preload-modules
 
 unit-testing-rum:
   stage: test