Add method and enctype to manifest (#11767)

app/serializers/manifest_serializer.rb

@@ -55,6 +55,8 @@ class ManifestSerializer < ActiveModel::Serializer
     {
       url_template: 'share?title={title}&text={text}&url={url}',
       action: 'share',
+      method: 'GET',
+      enctype: 'application/x-www-form-urlencoded',
       params: {
         title: 'title',
         text: 'text',