Alias `assign_attributes` to `attributes=` for `AttributeAssignment`

There is no reason `attributes=` doesn't take `assign_attributes`.

activemodel/lib/active_model/attribute_assignment.rb

@@ -35,6 +35,8 @@ module ActiveModel
       _assign_attributes(sanitize_for_mass_assignment(attributes))
     end
 
+    alias attributes= assign_attributes
+
     private
 
       def _assign_attributes(attributes)

activemodel/test/cases/attribute_assignment_test.rb

@@ -68,6 +68,14 @@ class AttributeAssignmentTest < ActiveModel::TestCase
     assert_equal "world", model.description
   end
 
+  test "simple assignment alias" do
+    model = Model.new
+
+    model.attributes = { name: "hello", description: "world" }
+    assert_equal "hello", model.name
+    assert_equal "world", model.description
+  end
+
   test "assign non-existing attribute" do
     model = Model.new
     error = assert_raises(ActiveModel::UnknownAttributeError) do

activerecord/lib/active_record/attribute_assignment.rb

@@ -6,11 +6,6 @@ module ActiveRecord
   module AttributeAssignment
     include ActiveModel::AttributeAssignment
 
-    # Alias for ActiveModel::AttributeAssignment#assign_attributes. See ActiveModel::AttributeAssignment.
-    def attributes=(attributes)
-      assign_attributes(attributes)
-    end
-
     private
 
       def _assign_attributes(attributes)