Fix form build spec

In Rails 8 the input helper for `<textarea>` HTML tag is finally
called `textarea` and not `text_area` anymore.

spec/libraries/forms/builder_spec.rb

@@ -100,15 +100,17 @@
         "Template",
         controller: controller,
         label: "<label>",
-        text_area: "<textarea>",
+        textarea: "<textarea>",
+        text_area: "<textarea>", # need to support Rails 7
         content_tag: "<alchemy-tinymce>"
       )
     end
 
     subject { builder.richtext(attribute) }
 
     it "uses a alchemy-tinymce" do
-      expect(template).to receive(:text_area).with(
+      receiving_method = (Rails::VERSION::MAJOR >= 8) ? :textarea : :text_area
+      expect(template).to receive(receiving_method).with(
         "Ding",
         :foo,
         hash_including(