Mixfile: extra_applications instead of applications

[mweidner037]

When attempting to publish from my local machine with Elixir 1.17 (or 1.15), I encountered the issue described here, which is due to the applications: key in the Mixfile. I'm guessing newer versions of mix require applications not listed there.

This PR attempts to fix the issue by using extra_applications instead of applications and eliminating entries that should start automatically (because they are included in deps). The change is per the docs in mix help compile.app:

:extra_applications - a list of OTP applications your application
    depends on which are not included in :deps (usually defined in deps/0 in
    your mix.exs). For example, here you can declare a dependency on
    applications that ship with Erlang/OTP or Elixir, like :crypto or :logger.
    Optional extra applications can be declared as a tuple, such as {:ex_unit,
    :optional}. Mix guarantees all non-optional applications are started before
    your application starts.

With these changes, I am now able to run mix docs locally, which hopefully means that mix hex.publish will work too. However, I am not sure whether the changes will affect consumers of the package, and if so, how to test its effect on them.

[scottmessinger]

great! Thank you!