Maintenance: Work around timeouts caused by the sanitizer in slow CI environments.

spec/models/channel/email_parser_spec.rb

@@ -1236,6 +1236,12 @@ RSpec.describe Channel::EmailParser, type: :model do
     end
 
     describe 'XSS protection' do
+
+      before do
+        # XSS processing may run into a timeout on slow CI systems, so turn the timeout off for the test.
+        stub_const("#{HtmlSanitizer}::PROCESSING_TIMEOUT", nil)
+      end
+
       let(:article) { described_class.new.process({}, raw_mail).second }
 
       let(:raw_mail) { <<~RAW.chomp }