Support Bootsnap in Ruby 3

.github/workflows/tests.yml

@@ -326,7 +326,6 @@ jobs:
         if: matrix.ruby
         run: |
           echo "HOMEBREW_USE_RUBY_FROM_PATH=1" >> "${GITHUB_ENV}"
-          echo "HOMEBREW_BOOTSNAP=" >> "${GITHUB_ENV}" # Unsupported, for now
           rm -rf "${{ steps.set-up-homebrew.outputs.repository-path }}/Library/Homebrew/vendor/portable-ruby"
 
       - run: brew config

Library/Homebrew/startup/bootsnap.rb

@@ -3,9 +3,7 @@
 
 # Disable Rails cops, as we haven't required active_support yet.
 # rubocop:disable Rails
-homebrew_bootsnap_enabled = ENV["HOMEBREW_NO_BOOTSNAP"].nil? &&
-                            !ENV["HOMEBREW_BOOTSNAP"].nil? &&
-                            ENV["HOMEBREW_RUBY3"].nil?
+homebrew_bootsnap_enabled = ENV["HOMEBREW_NO_BOOTSNAP"].nil? && !ENV["HOMEBREW_BOOTSNAP"].nil?
 
 # we need some development tools to build bootsnap native code
 homebrew_bootsnap_enabled &&= if ENV["HOMEBREW_MACOS_VERSION"]