Fixes #38115 - Drop Ruby 2.7 support

We no longer have deployment targets with these versions and it's
holding back use of the latest libraries.

Author: ekohl

.github/matrix.json

@@ -1,5 +1,5 @@
 {
   "postgresql": ["13"],
-  "ruby": ["2.7", "3.0"],
+  "ruby": ["3.0"],
   "node": ["18"]
 }

app/models/subnet.rb

@@ -208,14 +208,14 @@ def ipaddr
   def cidr
     return if mask.nil?
     IPAddr.new(mask).to_i.to_s(2).count("1")
-  rescue invalid_address_error
+  rescue IPAddr::InvalidAddressError
     nil
   end
 
   def cidr=(cidr)
     return if cidr.nil?
     self[:mask] = IPAddr.new(in_mask, family).mask(cidr).to_s
-  rescue invalid_address_error
+  rescue IPAddr::InvalidAddressError
     nil
   end
 
@@ -438,10 +438,4 @@ def new_network_type(args)
       raise ::Foreman::Exception.new N_("unknown network_type")
     end
   end
-
-  def invalid_address_error
-    # IPAddr::InvalidAddressError is undefined for ruby 1.9
-    return IPAddr::InvalidAddressError if IPAddr.const_defined?('InvalidAddressError')
-    ArgumentError
-  end
 end

config/application.rb

@@ -161,7 +161,7 @@ class Application < Rails::Application
     # Disable fieldWithErrors divs
     config.action_view.field_error_proc = proc { |html_tag, instance| html_tag.to_s.html_safe }
 
-    # Configure the default encoding used in templates for Ruby 1.9.
+    # Configure the default encoding used in templates
     config.encoding = "utf-8"
 
     # Configure sensitive parameters which will be filtered from the log file.

config/boot.rb

@@ -2,7 +2,7 @@
 
 unless File.exist?(File.expand_path('../Gemfile.in', __dir__))
   ENV['BUNDLE_GEMFILE'] ||= File.expand_path('../Gemfile', __dir__)
-  # Set up boootsnap on Ruby 2.7+ in development and test env with Bundler enabled and development/test group
+  # Set up boootsnap in development and test env with Bundler enabled and development/test group
   early_env = ENV["RAILS_ENV"] || ENV["RACK_ENV"] || "development"
   require 'active_support/dependencies'
   require('bootsnap/setup') if %w[development test].include?(early_env) && File.exist?(ENV['BUNDLE_GEMFILE']) && !Gem::Specification.stubs_for("bootsnap").empty?