fix: prevent ecto/pg from getting confused about the type of maps

lib/expr.ex

@@ -1594,10 +1594,13 @@ defmodule AshPostgres.Expr do
 
   defp do_dynamic_expr(query, value, bindings, embedded?, acc, _type)
        when is_map(value) and not is_struct(value) do
-    Enum.reduce(value, {%{}, acc}, fn {key, value}, {map, acc} ->
-      {value, acc} = do_dynamic_expr(query, value, bindings, embedded?, acc)
-      {Map.put(map, key, value), acc}
-    end)
+    {value, acc} =
+      Enum.reduce(value, {%{}, acc}, fn {key, value}, {map, acc} ->
+        {value, acc} = do_dynamic_expr(query, value, bindings, embedded?, acc)
+        {Map.put(map, key, value), acc}
+      end)
+
+    {Ecto.Query.dynamic([], type(^value, :map)), acc}
   end
 
   defp do_dynamic_expr(query, other, bindings, true, acc, type) do

test/bulk_update_test.exs

@@ -34,6 +34,17 @@ defmodule AshPostgres.BulkUpdateTest do
     |> Enum.map(& &1.list_of_stuff)
   end
 
+  test "a map can be given as input on a regular update" do
+    %{records: [post | _]} =
+      Api.bulk_create!([%{title: "fred"}, %{title: "george"}], Post, :create,
+        return_records?: true
+      )
+
+    post
+    |> Ash.Changeset.for_update(:update, %{list_of_stuff: [%{a: [:a, :b]}, %{a: [:c, :d]}]})
+    |> Api.update!()
+  end
+
   test "bulk updates only apply to things that the query produces" do
     Api.bulk_create!([%{title: "fred"}, %{title: "george"}], Post, :create)