I asked GPT. This help me.

def patch_grpc_template_error
  files_to_patch = [
    'Pods/gRPC-Core/src/core/lib/promise/detail/basic_seq.h',
    'Pods/gRPC-C++/src/core/lib/promise/detail/basic_seq.h'
  ]

  files_to_patch.each do |file|
    if File.exist?(file)
      puts "⚙️ sed patch: #{file}"
      system("sed -i '' 's/Traits::template CallSeqFactory/Traits::CallSeqFactory/' #{file}")
    end
  end
end

post_install do |installer|
  patch_grpc_template_error
end