improvement: use struct spec to avoid double % in struct inspect

currently, inspecting an `OpenApiSpex.Schema` looks like this:

`%OpenApiSpex.Schema%{type: :object}`

with the new change, it looks like this:

`%OpenApiSpex.Schema{type: :object}`

which allows copy/pasting the struct

lib/open_api_spex/inspect/for_schema.ex

@@ -11,6 +11,12 @@ defimpl Inspect, for: OpenApiSpex.Schema do
       end)
       |> Map.new()
 
-    concat(["%OpenApiSpex.Schema", to_doc(map, opts)])
+    infos =
+      for %{field: field} = info <- OpenApiSpex.Schema.__info__(:struct),
+          Map.has_key?(map, field),
+          field not in [:__struct__, :__exception__],
+          do: info
+
+     Inspect.Map.inspect(map, Macro.inspect_atom(:literal, OpenApiSpex.Schema), infos, opts)
   end
 end