(PA-5646) Pin to OpenSSL 1.1 Ruby 2.7

Homebrew recently updated its Ruby 2.7 formula to use OpenSSL 3.0
instead of 1.1:

Homebrew/homebrew-core@fb4bb76

Ruby 2.7 does not support OpenSSL 3.0, so using Homebrew's updated
formula causes test failures for puppet-agent.

This commit switches our Vanagon projects to use the last version of
Homebrew's Ruby 2.7 formula prior to the switch over to OpenSSL 3.0.

configs/components/_base-ruby.rb

@@ -59,9 +59,10 @@
 elsif platform.is_macos?
  pkg.environment 'optflags', settings[:cflags]
  if platform.is_cross_compiled?
- # Pin to an older version of ruby@2.5. This can be removed once we're no longer cross-compiling
- if ruby_version_y == "2.5"
- pkg.build_requires "puppetlabs/puppet/ruby@2.5"
+ # Pin to an older version of ruby@2.7 hosted by Puppet as Homebrew
+ # moved its Ruby 2.7 formula from OpenSSL 1.1 to 3.0
+ if ruby_version_y == "2.7"
+ pkg.build_requires "puppetlabs/puppet/ruby@2.7"
  else
  pkg.build_requires "ruby@#{ruby_version_y}"
  end