[ci] Don't spam the rspec progress with puma startup

Before:
Packages
  editing package files
Capybara starting Puma...
* Version 3.12.0 , codename: Llamas in Pajamas
* Min threads: 0, max threads: 4
* Listening on tcp://0.0.0.0:3005
    editing an existing file

After:
Packages
  editing package files
    editing an existing file