Igniter install should have default prompt

[bcardarella]

For example:

Update: mix.exs

     ...|
34 34   |  defp deps do
35 35   |    [
   36 + |      {:beacon_live_admin, "~> 0.2"},
   37 + |      {:beacon, "~> 0.2"},
36 38   |      {:igniter, "~> 0.4"},
37 39   |      {:phoenix, "~> 1.7.14"},
     ...|


These dependencies should be installed before continuing. Modify mix.exs and install? [y/n]

this should probably have [Y/n] as the prompt to imply if I just <enter> it will default to an opt-in