Where possible, use built-in JSON instead of Jason

Note that it's not possible to replace any call where we encode and
pretty print, as JSON doesn't have such functionality.

lib/last_fm/api_impl.ex

@@ -133,7 +133,7 @@ defmodule LastFm.APIImpl do
 
     case Finch.request(req, LastFm.Finch, @request_opts) do
       {:ok, response} when response.status == 200 ->
-        Jason.decode(response.body)
+        JSON.decode(response.body)
         |> identify_body()
 
       other ->

lib/mix/tasks/music_brainz/refresh_fixtures.ex

@@ -33,7 +33,7 @@ defmodule Mix.Tasks.MusicBrainz.RefreshFixtures do
         {:ok, body} ->
           # store the fixture pretty printed
           dest = Path.join(@fixtures_folder, filename)
-          content = body |> Jason.decode!() |> Jason.encode!(pretty: true)
+          content = body |> JSON.decode!() |> Jason.encode!(pretty: true)
           File.write!(dest, content)
 
         {:error, msg} ->

lib/music_brainz/api_impl.ex

@@ -439,7 +439,7 @@ defmodule MusicBrainz.APIImpl do
 
     case Finch.request(req, MusicBrainz.Finch) do
       {:ok, response} when response.status == 200 ->
-        {:ok, Jason.decode!(response.body)}
+        {:ok, JSON.decode!(response.body)}
 
       {:ok, response} when response.status in 301..308 ->
         location = :proplists.get_value("location", response.headers)

lib/open_ai.ex

@@ -11,7 +11,7 @@ defmodule OpenAI do
       end
     end)
 
-    result = Agent.get(collector, & &1) |> Jason.decode!()
+    result = Agent.get(collector, & &1) |> JSON.decode!()
     Agent.stop(collector)
     {:ok, result}
   end

lib/open_ai/api.ex

@@ -64,7 +64,7 @@ defmodule OpenAI.API do
 
   defp decode_body("", _), do: :ok
   defp decode_body("[DONE]", _), do: :ok
-  defp decode_body(json, cb), do: cb.(Jason.decode!(json))
+  defp decode_body(json, cb), do: cb.(JSON.decode!(json))
 
   defp api_key do
     Application.get_env(:music_library, OpenAI)