Only check pid ancestors for inline override

Ancestors may be registered names such as atoms or global tuples, and
not necessarily a pid. Now the process dictionary is only checked for
pid ancestors.

lib/oban/config.ex

@@ -163,12 +163,14 @@ defmodule Oban.Config do
     end
   end
 
-  defp inline_testing?(pid, default) do
+  defp inline_testing?(pid, default) when is_pid(pid) do
     {:dictionary, dictionary} = Process.info(pid, :dictionary)
 
     Keyword.get(dictionary, :oban_testing, default) == :inline
   end
 
+  defp inline_testing?(_pid, _default), do: false
+
   @doc false
   @spec node_name(%{optional(binary()) => binary()}) :: binary()
   def node_name(env \\ System.get_env()) do

test/oban/testing_test.exs

@@ -405,6 +405,8 @@ defmodule Oban.TestingTest do
 
       Testing.with_testing_mode(:inline, fn ->
         fun = fn ->
+          Process.put(:"$ancestors", [Some.Endpoint | Process.get(:"$ancestors")])
+
           Oban.insert!(name, Worker.new(%{ref: 1, action: "OK"}))
 
           assert_received {:ok, 1}