Generated html_part breaking tests after upgrade to 1.11.0

[sajan45]

After upgrading to 1.11.0 from 1.10.3, assertions in my app is breaking. The only difference is email.html_part.body.to_s gives an HTML with a \r at the end of each line. I think this is the PR #248 that changed how html_part is generated. We use Rails 7.0.8, premailer 1.22, and standard ERB files for mailer views, nothing unusual that I can see. I don't know what other info could be helpful. Please let me know if you need any other details.