Phoenix 1.7 upgrade

[gagandeepb]

Upgrading Phoenix from 1.6 to 1.7.

Some comments:

• phoenix_view is now a separate package and needs to be added.
• Elixir version in mix file is now in sync with the .tool-versions file.
• Fixing of one failling test that relies on internal implementation/non-public interface of Phoenix.Router:
  (Old arg order in Phoenix 1.6: https://github.com/phoenixframework/phoenix/blob/9da43f0313482ea8eb62e7345cc9b8f18be087ef/lib/phoenix/router.ex#L433
  New arg order in Phoenix 1.7.12:
  https://github.com/phoenixframework/phoenix/blob/bdc2d7398ac51514d964e02e302515d2ce95b6ff/lib/phoenix/router.ex#L584)
• The last point above hints at future opportunities for refactor of the api_redirector module from a plug to a controller (assuming there is some broad agreement) in order to not have to rely on reflection/non-public interfaces.

[coveralls]

coverage: 95.056%. remained the same
when pulling 201d48c on phoenix-1_7-upgrade
into f39a82c on main.

[nelsonkopliku]

Super! Thanks!

[dottorblaster]

Great work @gagandeepb! If you want you can also have a stab at migrating from the old views to the new JSON rendering feature:

https://hexdocs.pm/phoenix/json_and_apis.html#rendering-json

Anyway, thank you so much!

[gagandeepb]

@dottorblaster Thanks. I am not quite sure how the JSON rendering feature interacts with the open_api_spex schema format/serialization. I suspect/guess there might be some duplication of this Ser/De logic somewhere if both approaches were to co-exist, and this might need a deeper look/some internal conversations before proceeding.