Bug#921320: ruby-rspec-rails build depends on ruby-capybara (>= 2.15~) that is currently not in buster

[Adrian Bunk]

Source: ruby-rspec-rails
Version: 3.8.1-2
Severity: serious
Tags: ftbfs
Control: block -1 by 900156

ruby-rspec-rails build depends on ruby-capybara (>= 2.15~)
that is currently not in buster due to #900156.