When compiling, Mix complains with warnings

[jonathonadler]

==> formulator
Compiling 5 files (.ex)
warning: Phoenix.HTML.__using__/1 defined in application :phoenix_html is used by the current application but the current application does not depend on :phoenix_html. To fix this, you must do one of:

  1. If :phoenix_html is part of Erlang/Elixir, you must include it under :extra_applications inside "def application" in your mix.exs

  2. If :phoenix_html is a dependency, make sure it is listed under "def deps" in your mix.exs

  3. In case you don't want to add a requirement to :phoenix_html, you may optionally skip this warning by adding [xref: [exclude: [Phoenix.HTML]]] to your "def project" in mix.exs

Found at 3 locations:
  lib/formulator.ex:2: Formulator
  lib/formulator/html_builder.ex:2: Formulator.HtmlBuilder
  lib/formulator/input.ex:2: Formulator.Input
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