Bump premailer to 1.27.0 to stop css_parser deprecation warnings

What does this MR do and why?

Since 19.4, every email that goes through premailer writes this line to stderr:

premailer-1.23.0/lib/premailer/adapter/nokogiri.rb:65: warning: [DEPRECATION] positional arguments are deprecated use keyword instead.

css_parser (now 1.22.0 in our bundle) deprecated positional arguments, and premailer 1.23.0 still uses them. On GitLab Dedicated this produced millions of log lines a day and throttled the log pipeline (see the issue).

This bumps premailer from 1.23.0 to 1.27.0 in Gemfile.lock and Gemfile.next.lock. Premailer 1.26.0 moved to keyword arguments ("Bump css_parser to 1.19 to avoid deprecations"). 1.27.0 only adds multiline inline style support on top of that.

I picked 1.27.0 rather than the latest (1.32.0) to keep the change small and easy to backport to 19.4. 1.30.0 rewrote how the Nokogiri adapter folds styles, which is a bigger change for a fix like this.

premailer-rails 1.12.0 accepts premailer (~> 1.7, >= 1.7.9), so no other gem changes. The checksum matches rubygems.org.

References

Closes #636290 (closed)

How to set up and validate locally

I reproduced it outside the app with css_parser 1.22.0:

require "premailer"
Premailer.new("<html><head><style>p{color:red}</style></head><body><p>x</p></body></html>",
  with_html_string: true, adapter: :nokogiri).to_inline_css

• premailer 1.23.0: prints the deprecation warning above.
• premailer 1.27.0: no warning, same output.

In the app, bundle exec rspec spec/initializers/action_mailer_hooks_spec.rb passes with 1.27.0. I couldn't run the mailer specs locally (my setup can't compile the email stylesheets), so the CI mailer specs are the real check here.

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