Fix new rubocop warnings

.rubocop.yml

@@ -68,9 +68,6 @@ Rails/SkipsModelValidations:
     - 'db/migrate/*.rb'
     - 'app/controllers/users_controller.rb'
 
-Style/ArgumentsForwarding:
-  Enabled: false
-
 Style/Documentation:
   Enabled: false
 

test/helpers/asset_helper_test.rb

@@ -2,6 +2,6 @@ require "test_helper"
 
 class AssetHelperTest < ActionView::TestCase
   def test_assets
-    assert assets("iD").is_a?(Hash)
+    assert_kind_of Hash, assets("iD")
   end
 end

test/lib/i18n_test.rb

@@ -42,7 +42,7 @@ class I18nTest < ActiveSupport::TestCase
 
             assert_includes value, :other, "#{key}.other plural key missing"
           else
-            assert value.is_a?(String), "#{key} is not a string"
+            assert_kind_of String, value, "#{key} is not a string"
 
             value.scan(/%\{(\w+)\}/) do
               assert_includes variables, Regexp.last_match(1), "#{key} uses unknown interpolation variable #{Regexp.last_match(1)}"