refactor inertia html headers setter

Author: PedroAugustoRamalhoDuarte

lib/inertia_rails/controller.rb

@@ -55,6 +55,10 @@ def inertia_headers
       @_inertia_html_headers.join.html_safe
     end
 
+    def inertia_headers=(value)
+      @_inertia_html_headers = value
+    end
+
     def default_render
       if InertiaRails.default_render?
         render(inertia: true)

lib/inertia_rails/renderer.rb

@@ -32,7 +32,7 @@ def render_ssr
       uri = URI("#{::InertiaRails.ssr_url}/render")
       res = JSON.parse(Net::HTTP.post(uri, page.to_json, 'Content-Type' => 'application/json').body)
 
-      @controller.instance_variable_set("@_inertia_html_headers", res['head'])
+      @controller.inertia_headers = res['head']
       @render_method.call html: res['body'].html_safe, layout: layout, locals: (view_data).merge({page: page})
     end