Ignore googlefont stylesheet from premailer

We do not need to run this through premailer since the @font-face rules
cannot be inlined into the HTML elements

app/views/notify/in_product_marketing_email.html.haml

@@ -3,7 +3,7 @@
   %head
     %meta{ content: "text/html; charset=utf-8", "http-equiv" => "Content-Type" }
     %meta{ content: "width=device-width, initial-scale=1", name: "viewport" }
-    %link{ href: "https://fonts.googleapis.com/css?family=Source+Sans+Pro:400,600", rel: "stylesheet", type: "text/css" }
+    %link{ href: "https://fonts.googleapis.com/css?family=Source+Sans+Pro:400,600", rel: "stylesheet", type: "text/css", data: { premailer: 'ignore' } }
     %title= message.subject
     :css
       /* CLIENT-SPECIFIC STYLES */

spec/mailers/notify_spec.rb

@@ -1969,6 +1969,19 @@ RSpec.describe Notify do
     end
   end
 
+  describe 'in product marketing', :mailer do
+    let_it_be(:group) { create(:group) }
+
+    let(:mail) { ActionMailer::Base.deliveries.last }
+
+    it 'does not raise error' do
+      described_class.in_product_marketing_email(user.id, group.id, :trial, 0).deliver
+
+      expect(mail.subject).to eq('Go farther with GitLab')
+      expect(mail.body.parts.first.to_s).to include('Start a GitLab Ultimate trial today in less than one minute, no credit card required.')
+    end
+  end
+
   def expect_sender(user)
     sender = subject.header[:from].addrs[0]
     expect(sender.display_name).to eq("#{user.name} (@#{user.username})")