Merge pull request #19511 from Homebrew/doctor-arm64-linux

os/linux/diagnostic: skip error on arm64 when `HOMEBREW_ARM64_TESTING` is set

Library/Homebrew/extend/os/linux/diagnostic.rb

@@ -74,7 +74,8 @@ module OS
         end
 
         def check_supported_architecture
-          return if Hardware::CPU.arch == :x86_64
+          return if Hardware::CPU.intel?
+          return if Homebrew::EnvConfig.developer? && ENV["HOMEBREW_ARM64_TESTING"].present? && Hardware::CPU.arm?
 
           <<~EOS
             Your CPU architecture (#{Hardware::CPU.arch}) is not supported. We only support