build warning

[sparrell]

fix:

Generated phoenix_live_view app
warning: Phoenix now requires you to explicitly list which engine to use
for Phoenix JSON encoding. We recommend everyone to upgrade to
Jason by setting in your config/config.exs:

config :phoenix, :json_library, Jason

And then adding {:jason, "~> 1.0"} as a dependency.

If instead you would rather continue using Poison, then add to
your config/config.exs:

config :phoenix, :json_library, Poison

(phoenix 1.5.4) lib/phoenix.ex:38: Phoenix.start/2
(kernel 6.5.2.1) application_master.erl:277: :application_master.start_it_old/4

[sparrell]

might not be fixable. we appear to have the exact lines they requested, yet we still get the error